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compat.info (135545B)

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 Copyright © 2022-2024 Free Software Foundation, Inc.
 
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 INFO-DIR-SECTION Emacs
 START-INFO-DIR-ENTRY
 * Compat: (compat).     Compatibility Library for Emacs Lisp.
 END-INFO-DIR-ENTRY
 
 
 File: docXccUUB.info,  Node: Top,  Next: Introduction,  Up: (dir)
 
 "Compat" Manual
 ***************
 
 This manual documents the usage of the "Compat" Emacs lisp library, the
 forward-compatibility library for Emacs Lisp, corresponding to version
 29.1.4.5.
 
    Copyright © 2022-2024 Free Software Foundation, Inc.
 
      Permission is granted to copy, distribute and/or modify this
      document under the terms of the GNU Free Documentation License,
      Version 1.3 or any later version published by the Free Software
      Foundation; with no Invariant Sections, with the Front-Cover Texts
      being “A GNU Manual,” and with the Back-Cover Texts as in (a)
      below.  A copy of the license is included in the section entitled
      “GNU Free Documentation License.”
 
      (a) The FSF’s Back-Cover Text is: “You have the freedom to copy and
      modify this GNU manual.”
 
 * Menu:
 
 * Introduction::
 * Support::
 * Development::
 * Function Index::
 * Variable Index::
 
 — The Detailed Node Listing —
 
 Introduction
 
 * Overview::
 * Usage::
 * Limitations::
 
 Support
 
 * Emacs 25.1::                   Compatibility support for Emacs 25.1
 * Emacs 26.1::                   Compatibility support for Emacs 26.1
 * Emacs 27.1::                   Compatibility support for Emacs 27.1
 * Emacs 28.1::                   Compatibility support for Emacs 28.1
 * Emacs 29.1::                   Compatibility support for Emacs 29.1
 
 
 
 File: docXccUUB.info,  Node: Introduction,  Next: Support,  Prev: Top,  Up: Top
 
 1 Introduction
 **************
 
 * Menu:
 
 * Overview::
 * Usage::
 * Limitations::
 
 
 File: docXccUUB.info,  Node: Overview,  Next: Usage,  Up: Introduction
 
 1.1 Overview
 ============
 
 The objective of Compat is to provide "forwards compatibility" library
 for Emacs Lisp.  By using Compat, an Elisp package does not have to make
 the decision to either use new and useful functionality or support old
 versions of Emacs.
 
    The library provides support back until Emacs 24.4.  The intended
 audience are package developers that are interested in using newer
 developments, without having to break compatibility.
 
 
 File: docXccUUB.info,  Node: Usage,  Next: Limitations,  Prev: Overview,  Up: Introduction
 
 1.2 Usage
 =========
 
 The intended use-case for this library is for package developers to add
 as a dependency in the header.  The version of the Compat library
 mirrors the version of Emacs releases.  The current version of Compat
 corresponds to the current Emacs release.
 
      ;; Package-Requires: ((emacs "24.4") (compat "29.1.4.5"))
 
    There is no need to depend on ‘emacs 24.4’ specifically.  One can
 choose any newer version, if features not provided by Compat necessitate
 it, for example bug fixes or UI improvements.
 
    In any file where compatibility forms are used, a
 
      (require 'compat)
 
    should be added early on.  This will load all necessary Compat
 definitions.  Compat loads the ‘seq’ library which is preloaded by
 default on Emacs 29.  Note that if Compat is installed on a recent
 version of Emacs, all of the definitions are disabled at compile time,
 such that no negative performance impact is incurred.
 
    A minimal version of Compat will be present in Emacs version 30 and
 newer.  Packages which are part of Emacs itself and want to take
 advantage of Compat, can also use ‘(require 'compat)’.  The advantage of
 the inclusion of a minimal Compat in Emacs is that Compat will not be
 installed if you require a version newer or equal than the current Emacs
 version.  For example, if a package depending on Emacs 25.1 and Compat
 29.1 is installed on Emacs 30.1, Compat will not be pulled in as
 dependency, since Emacs 30.1 already provides the required
 functionality.
 
    Compat provides replacement functions with extended functionality for
 functions that are already defined, e.g., ‘sort’ or ‘assoc’.  These
 functions may have changed their calling convention (additional optional
 arguments) or may have changed their behavior.  These functions must be
 looked up explicitly with ‘compat-function’ or called explicitly with
 ‘compat-call’.  We call them “Extended Definitions”.  In contrast, newly
 “Added Definitions” can be called as usual.  The Compat manual
 explicitly documents the calling convention of each compatibility
 function.
 
      (compat-call assoc key alist testfn) ;; Call extended `assoc'
      (mapcan fun seq)                     ;; Call newly added `mapcan'
 
  -- Macro: compat-call fun &rest args
      This macro calls the compatibility function FUN with ARGS.  Many
      functions provided by Compat can be called directly without this
      macro.  However in the case where Compat provides an alternative
      version of an existing function, the function call has to go
      through ‘compat-call’.  This happens for example when the calling
      convention of a function has changed.
 
  -- Macro: compat-function fun
      This macro returns the compatibility function symbol for FUN.  See
      ‘compat-call’ for a more convenient macro to directly call
      compatibility functions.
 
    If Compat is used in Emacs core packages, the macros ‘compat-call’
 and ‘compat-function’ will be available in Emacs version 30 and newer.
 
    The macros ‘compat-call’ and ‘compat-function’ are introduced by
 Compat, since Compat does not advise or override existing functions.
 Generally Compat is written in defensive style which is supposed to
 reduce potential breakage, and to increase the chances of staying binary
 compatible across releases.  The extensive test coverage ensures that we
 can maintain high quality, which is crucial for Compat which is not
 restricted to a namespace like usual libraries.
 
    If you intend to use a compatibility function in your code it is
 recommended that you take a look at the test suite ‘compat-tests.el’.
 There you can see the supported calling conventions, which are
 guaranteed to work on the supported Emacs versions.  We ensure this
 using continuous integration.  All functions provided by Compat are
 covered by the test suite.  There is a link to the corresponding test on
 the first line of each definition.
 
    You may want to subscribe to the compat-announce
 (https://lists.sr.ht/~pkal/compat-announce) mailing list to be notified
 when new versions are released or relevant changes are made.  We also
 provide a development mailing list
 (https://lists.sr.ht/~pkal/compat-devel) (~pkal/compat-devel@lists.sr.ht
 <~pkal/compat-devel@lists.sr.ht>).
 
 
 File: docXccUUB.info,  Node: Limitations,  Prev: Usage,  Up: Introduction
 
 1.3 Limitations
 ===============
 
 The Compat library has a number of limitations.  Complete backwards
 compatibility cannot be provided due to the scope of Compat and for
 technical reasons.  The scope is intentionally restricted in order to
 limit the size of Compat and to ensure that the library stays
 maintainable.
 
    Emacs version 24.4 is chosen as the oldest version supported by
 Compat, since Elisp has seen significant changes at that version.  Since
 24.4 Emacs major versions consistently bump the major version number.
 On the library level, subr-x was introduced in 24.4.  Most popular Emacs
 packages already require 24.4 or even newer versions of Emacs.
 Supporting for more historical Emacs versions would complicate
 maintenance while only few packages and users would benefit.
 
    Below we list a number of reasons why certain functionality cannot be
 provided.  Note that in some special cases exceptions can be made and
 functions can still be added to Compat even if they satisfy the criteria
 from the list.  In case you miss functionality which you think should
 belong here, a *note report: Development. would be much appreciated.
 
    • The additional functionality is a command or a user-facing minor or
      major mode.  Compat is limited to functionality on the “library
      level”.  Generally functions provided by Compat are
      non-interactive, such that the user interface (M-x) is unaffected
      by the presence of Compat.
 
    • The function is not useful for package authors or not intended to
      be used by packages, but is only useful on the configuration level.
      The macro ‘setopt’ is such an example.
 
    • Private (double dashed) functions are not ported back.  If Compat
      includes some private functions, they are meant purely for internal
      usage.
 
    • The added or extended function belongs to the “application level”
      and not the “library level”.  Features which are not preloaded
      often belong to the “application level”.  Application examples are
      programming modes or modes like Dired, IRC and Gnus.  If these
      modes are extended with new functions, these are not ported back.
 
    • An existing function or macro was extended by some new
      functionality.  To support these cases, the function or macro would
      have to be advised.  Since this is invasive and adds significant
      overhead, even when the new feature is not used, Compat does not
      use advices.  As a compromise, compatibility functions and macros
      with a changed calling convention or behavior can be accessed via
      the ‘compat-function’ and ‘compat-call’ macros.  In this manual we
      call such definitions “Extended Definitions”.  An example is the
      function ‘plist-get’.  Note that extended functions are subject to
      closer scrutiny, since their usage via ‘compat-call’ is not
      completely painless.  If a particular extended function does not
      see much usage or the extension yields only marginal benefits, we
      may not provide it as part of Compat.
 
    • Bug fixes are usually not ported back as part of Compat.  Sometimes
      library functions show wrong behavior for edge cases.  In those
      cases Compat could in principle provide a compatibility function
      which is invoked via ‘compat-call’.  Such extended definitions
      would increase the maintenance burden of Compat.  At the same time
      the benefits would be small given that Compat does not override
      existing definitions.
 
    • The definition belongs to an Emacs core package, which is also
      distributed via ELPA. Compat does not have to provide backward
      compatibility for core packages since the updated package can be
      installed directly from ELPA. Examples include the libraries xref,
      project, seq, map and transient.
 
    • New functionality depends on an entire new, non-trivial core
      library, which is infeasible to duplicate within Compat.  If a
      backport of such a library is required, the preferred approach is
      to either release the library separately on GNU ELPA as a core
      package or as a separately maintained GNU ELPA package.  An example
      is the iso8601 library.
 
    • New functionality was implemented in the C core, or depends on
      external libraries that cannot be reasonably duplicated in the
      scope of a compatibility library.  Sometimes new functions on the C
      level rely on internal data structures, which we cannot access,
      rendering a backport impossible.  For example a missing libxml or
      libtreesitter cannot be emulated.
 
    • The semantics of Elisp changed on a deep level.  For example the
      addition of big integer support in Emacs 27.1 cannot be replicated
      on the level of Compat.
 
 
 File: docXccUUB.info,  Node: Support,  Next: Development,  Prev: Introduction,  Up: Top
 
 2 Support
 *********
 
 This section goes into the features that Compat manages and doesn’t
 manage to provide for each Emacs version.
 
 * Menu:
 
 * Emacs 25.1::                   Compatibility support for Emacs 25.1
 * Emacs 26.1::                   Compatibility support for Emacs 26.1
 * Emacs 27.1::                   Compatibility support for Emacs 27.1
 * Emacs 28.1::                   Compatibility support for Emacs 28.1
 * Emacs 29.1::                   Compatibility support for Emacs 29.1
 
 
 File: docXccUUB.info,  Node: Emacs 25.1,  Next: Emacs 26.1,  Up: Support
 
 2.1 Emacs 25.1
 ==============
 
 2.1.1 Added Definitions
 -----------------------
 
 The following functions and macros are implemented in Emacs 25.1.  These
 functions are made available by Compat on Emacs versions older than
 25.1.
 
  -- User Option: text-quoting-style
      The value of this user option is a symbol that specifies the style
      Emacs should use for single quotes in the wording of help and
      messages.  If the option’s value is ‘curve’, the style is ‘like
      this’ with curved single quotes.  If the value is ‘straight’, the
      style is 'like this' with straight apostrophes.  If the value is
      ‘grave’, quotes are not translated and the style is `like this'
      with grave accent and apostrophe, the standard style before Emacs
      version 25.  The default value ‘nil’ acts like ‘curve’ if curved
      single quotes seem to be displayable, and like ‘grave’ otherwise.
 
      This option is useful on platforms that have problems with curved
      quotes.  You can customize it freely according to your personal
      preference.
 
  -- Function: region-bounds
      Return the boundaries of the region.  Value is a list of one or
      more cons cells of the form ‘(start . end)’.  It will have more
      than one cons cell when the region is non-contiguous, see
      ‘region-noncontiguous-p’ and ‘extract-rectangle-bounds’.
 
  -- Function: region-noncontiguous-p
      Return non-nil if the region contains several pieces.  An example
      is a rectangular region handled as a list of separate contiguous
      regions for each line.
 
  -- Macro: save-mark-and-excursion body...
      This macro is like ‘save-excursion’, but also saves and restores
      the mark location and ‘mark-active’.  This macro does what
      ‘save-excursion’ did before Emacs 25.1.
 
  -- Function: format-message string &rest objects
      This function acts like ‘format’, except it also converts any grave
      accents (`) and apostrophes (') in STRING as per the value of
      ‘text-quoting-style’.
 
      Typically grave accent and apostrophe in the format translate to
      matching curved quotes, e.g., "Missing `%s'" might result in
      "Missing ‘foo’".  *Note (elisp)Text Quoting Style::, for how to
      influence or inhibit this translation.
 
      *note (elisp)Formatting Strings::.
 
  -- Function: directory-name-p filename
      This function returns non-‘nil’ if FILENAME ends with a directory
      separator character.  This is the forward slash ‘/’ on GNU and
      other POSIX-like systems; MS-Windows and MS-DOS recognize both the
      forward slash and the backslash ‘\’ as directory separators.
 
      *Note (elisp)Directory Names::.
 
  -- Function: string-greaterp string1 string2
      This function returns the result of comparing STRING1 and STRING2
      in the opposite order, i.e., it is equivalent to calling
      ‘(string-lessp STRING2 STRING1)’.
 
      *Note (elisp)Text Comparison::.
 
  -- Macro: with-file-modes mode body...
      This macro evaluates the BODY forms with the default permissions
      for new files temporarily set to MODES (whose value is as for
      ‘set-file-modes’ above).  When finished, it restores the original
      default file permissions, and returns the value of the last form in
      BODY.
 
      This is useful for creating private files, for example.
 
      *Note (elisp)Changing Files::.
 
  -- Function: alist-get key alist &optional default remove
      This function is similar to ‘assq’.  It finds the first association
      ‘(KEY . VALUE)’ by comparing KEY with ALIST elements, and, if
      found, returns the VALUE of that association.  If no association is
      found, the function returns DEFAULT.
 
      This is a generalized variable (*note (elisp)Generalized
      Variables::) that can be used to change a value with ‘setf’.  When
      using it to set a value, optional argument REMOVE non-‘nil’ means
      to remove KEY’s association from ALIST if the new value is ‘eql’ to
      DEFAULT.
 
      *note (elisp)Association Lists::.
 
  -- Macro: if-let (bindings...) then &rest else...
      As with ‘let*’, BINDINGS will consist of ‘(SYMBOL VALUE-FORM)’
      entries that are evaluated and bound sequentially.  If all
      VALUE-FORM evaluate to non-‘nil’ values, then THEN is evaluated as
      were the case with a regular ‘let*’ expression, with all the
      variables bound.  If any VALUE-FORM evaluates to ‘nil’, ELSE is
      evaluated, without any bound variables.
 
      A binding may also optionally drop the SYMBOL, and simplify to
      ‘(VALUE-FORM)’ if only the test is of interest.
 
      For the sake of backwards compatibility, it is possible to write a
      single binding without a binding list:
 
           (if-let* (SYMBOL (test)) foo bar)
           ≡
           (if-let* ((SYMBOL (test))) foo bar)
 
  -- Macro: when-let (bindings...) &rest body
      As with ‘when’, if one is only interested in the case where all
      BINDINGS are non-nil.  Otherwise BINDINGS are interpreted just as
      they are by ‘if-let*’.
 
  -- Function: hash-table-empty hash-table
      Check whether HASH-TABLE is empty (has 0 elements).
 
  -- Macro: thread-first &rest forms
      Combine FORMS into a single expression by “threading” each element
      as the _first_ argument of their successor.  Elements of FORMS can
      either be an list of an atom.
 
      For example, consider the threading expression and it’s equivalent
      macro expansion:
 
           (thread-first
             5
             (+ 20)
             (/ 25)
             -
             (+ 40))
           ≡
           (+ (- (/ (+ 5 20) 25)) 40)
 
      Note how the single ‘-’ got converted into a list before threading.
      This example uses arithmetic functions, but ‘thread-first’ is not
      restricted to arithmetic or side-effect free code.
 
  -- Macro: thread-last &rest forms
      Combine FORMS into a single expression by “threading” each element
      as the _last_ argument of their successor.  Elements of FORMS can
      either be an list of an atom.
 
      For example, consider the threading expression and it’s equivalent
      macro expansion:
 
           (thread-first
             5
             (+ 20)
             (/ 25)
             -
             (+ 40))
           ≡
           (+ 40 (- (/ 25 (+ 20 5))))
 
      Note how the single ‘-’ got converted into a list before threading.
      This example uses arithmetic functions, but ‘thread-last’ is not
      restricted to arithmetic or side-effect free code.
 
  -- Function: macroexpand-1 form &optional environment
      This function expands macros like ‘macroexpand’, but it only
      performs one step of the expansion: if the result is another macro
      call, ‘macroexpand-1’ will not expand it.
 
      *Note Expansion: (elisp)Expansion.
 
  -- Function: macroexp-quote e
      Return an expression E such that ‘(eval e)’ is V.
 
  -- Function: macroexp-parse body
      Parse a function BODY into ‘(declarations . exps)’.
 
  -- Function: bool-vector &rest objects
      This function creates and returns a bool-vector whose elements are
      the arguments, OBJECTS.
 
      *Note (elisp)Bool-Vectors::.
 
 2.1.2 Extended Definitions
 --------------------------
 
 These functions must be called explicitly via ‘compat-call’, since their
 calling convention or behavior was extended in Emacs 25.1:
 
  -- Function: compat-call sort sequence predicate
      This function sorts SEQUENCE stably.  Note that this function
      doesn’t work for all sequences; it may be used only for lists and
      vectors.  If SEQUENCE is a list, it is modified destructively.
      This functions returns the sorted SEQUENCE and compares elements
      using PREDICATE.  A stable sort is one in which elements with equal
      sort keys maintain their relative order before and after the sort.
      Stability is important when successive sorts are used to order
      elements according to different criteria.
 
      *Note (elisp)Sequence Functions::.
 
      The compatibility version adds support for vectors to be sorted,
      not just lists.
 
 2.1.3 Missing Definitions
 -------------------------
 
 Compat does not provide support for the following Lisp features
 implemented in 25.1:
 
    • The function ‘macroexp-macroexpand’.
    • The macro ‘macroexp-let2*’.
    • The function ‘directory-files-recursively’.
    • New ‘pcase’ patterns.
    • The hook ‘prefix-command-echo-keystrokes-functions’ and
      ‘prefix-command-preserve-state-hook’.
    • The hook ‘pre-redisplay-functions’.
    • The function ‘make-process’.
    • Support for the variable ‘inhibit-message’.
    • The ‘define-inline’ functionality.
    • The functions ‘string-collate-lessp’ and ‘string-collate-equalp’.
    • The function ‘funcall-interactively’.
    • The function ‘buffer-substring-with-bidi-context’.
    • The function ‘font-info’.
    • The function ‘default-font-width’.
    • The function ‘window-font-height’ and ‘window-font-width’.
    • The function ‘window-max-chars-per-line’.
    • The function ‘set-binary-mode’.
    • The functions ‘bufferpos-to-filepos’ and ‘filepos-to-bufferpos’.
    • The ‘thunk’ library.
 
 
 File: docXccUUB.info,  Node: Emacs 26.1,  Next: Emacs 27.1,  Prev: Emacs 25.1,  Up: Support
 
 2.2 Emacs 26.1
 ==============
 
 2.2.1 Added Definitions
 -----------------------
 
 The following functions and macros are implemented in Emacs 26.1.  These
 functions are made available by Compat on Emacs versions older than
 26.1.
 
  -- Function: assoc-delete-all key alist
      This function is like ‘assq-delete-all’ except that it uses ‘equal’
      to compare elements.
 
  -- Function: read-answer question answers
      This function prompts the user with text in QUESTION, which should
      end in the ‘SPC’ character.  The function includes in the prompt
      the possible responses in ANSWERS by appending them to the end of
      QUESTION.  The possible responses are provided in ANSWERS as an
      alist whose elements are of the following form:
 
           (LONG-ANSWER SHORT-ANSWER HELP-MESSAGE)
 
      where LONG-ANSWER is the complete text of the user response, a
      string; SHORT-ANSWER is a short form of the same response, a single
      character or a function key; and HELP-MESSAGE is the text that
      describes the meaning of the answer.  If the variable
      ‘read-answer-short’ is non-‘nil’, the prompt will show the short
      variants of the possible answers and the user is expected to type
      the single characters/keys shown in the prompt; otherwise the
      prompt will show the long variants of the answers, and the user is
      expected to type the full text of one of the answers and end by
      pressing <RET>.  If ‘use-dialog-box’ is non-‘nil’, and this
      function was invoked by mouse events, the question and the answers
      will be displayed in a GUI dialog box.
 
      The function returns the text of the LONG-ANSWER selected by the
      user, regardless of whether long or short answers were shown in the
      prompt and typed by the user.
 
      Here is an example of using this function:
 
           (let ((read-answer-short t))
             (read-answer "Foo "
                '(("yes"  ?y "perform the action")
                  ("no"   ?n "skip to the next")
                  ("all"  ?! "perform for the rest without more questions")
                  ("help" ?h "show help")
                  ("quit" ?q "exit"))))
 
  -- Function: mapcan function sequence
      This function applies FUNCTION to each element of SEQUENCE, like
      ‘mapcar’, but instead of collecting the results into a list, it
      returns a single list with all the elements of the results (which
      must be lists), by altering the results (using ‘nconc’; *note
      (elisp)Rearrangement::).  Like with ‘mapcar’, SEQUENCE can be of
      any type except a char-table.
 
           ;; Contrast this: (mapcar #'list '(a b c d)) ⇒ ((a) (b) (c)
           (d)) ;; with this: (mapcan #'list '(a b c d)) ⇒ (a b c d)
 
      *Note (elisp)Mapping Functions::.
 
  -- Function: cXXXr
  -- Function: cXXXXr
      *Note (elisp)List Elements::.
 
  -- Function: gensym &optional prefix
      This function returns a symbol using ‘make-symbol’, whose name is
      made by appending ‘gensym-counter’ to PREFIX and incrementing that
      counter, guaranteeing that no two calls to this function will
      generate a symbol with the same name.  The prefix defaults to
      ‘"g"’.
 
  -- Variable: gensym-counter
      See ‘gensym’.
 
  -- Function: buffer-hash &optional buffer-or-name
      Return a hash of BUFFER-OR-NAME.  If ‘nil’, this defaults to the
      current buffer.  As opposed to ‘secure-hash’, this function
      computes the hash based on the internal representation of the
      buffer, disregarding any coding systems.  It’s therefore only
      useful when comparing two buffers running in the same Emacs, and is
      not guaranteed to return the same hash between different Emacs
      versions.  It should be somewhat more efficient on larger buffers
      than ‘secure-hash’ is, and should not allocate more memory.
 
  -- Macro: file-name-unquote name
      This macro removes the quotation prefix ‘/:’ from the file NAME, if
      any.  If NAME is a remote file name, the local part of NAME is
      unquoted.
 
  -- Function: file-name-quoted-p name
      This macro returns non-‘nil’, when NAME is quoted with the prefix
      ‘/:’.  If NAME is a remote file name, the local part of NAME is
      checked.
 
      *Note (elisp)File Name Expansion::.
 
  -- Function: file-name-quote name
      This macro adds the quotation prefix ‘/:’ to the file NAME.  For a
      local file NAME, it prefixes NAME with ‘/:’.  If NAME is a remote
      file name, the local part of NAME (*note (elisp)Magic File Names::)
      is quoted.  If NAME is already a quoted file name, NAME is returned
      unchanged.
 
           (substitute-in-file-name (compat-call file-name-quote "bar/~/foo")) ⇒
                "/:bar/~/foo"
 
           (substitute-in-file-name (compat-call file-name-quote "/ssh:host:bar/~/foo"))
                ⇒ "/ssh:host:/:bar/~/foo"
 
      The macro cannot be used to suppress file name handlers from magic
      file names (*note (elisp)Magic File Names::).
 
      *Note (elisp)File Name Expansion::.
 
  -- Function: make-nearby-temp-file prefix &optional dir-flag suffix
      This function is similar to ‘make-temp-file’, but it creates a
      temporary file as close as possible to ‘default-directory’.  If
      PREFIX is a relative file name, and ‘default-directory’ is a remote
      file name or located on a mounted file systems, the temporary file
      is created in the directory returned by the function
      ‘temporary-file-directory’.  Otherwise, the function
      ‘make-temp-file’ is used.  PREFIX, DIR-FLAG and SUFFIX have the
      same meaning as in ‘make-temp-file’.
 
           (let ((default-directory "/ssh:remotehost:")) (make-nearby-temp-file
             "foo")) ⇒ "/ssh:remotehost:/tmp/foo232J6v"
 
  -- Variable: mounted-file-systems
      A regular expression matching files names that are probably on a
      mounted file system.
 
  -- Function: temporary-file-directory
      The directory for writing temporary files via
      ‘make-nearby-temp-file’.  In case of a remote ‘default-directory’,
      this is a directory for temporary files on that remote host.  If
      such a directory does not exist, or ‘default-directory’ ought to be
      located on a mounted file system (see ‘mounted-file-systems’), the
      function returns ‘default-directory’.  For a non-remote and
      non-mounted ‘default-directory’, the value of the variable
      ‘temporary-file-directory’ is returned.
 
      *Note (elisp)Unique File Names::.
 
  -- Macro: if-let* (bindings...) then &rest else
      ‘if-let*’ is mostly equivalent to ‘if-let’, with the exception that
      the legacy ‘(if (VAR (test)) foo bar)’ syntax is not permitted.
 
  -- Macro: when-let* (bindings...) then &rest else
      ‘when-let*’ is mostly equivalent to ‘when-let’, with the exception
      that the legacy ‘(when-let (VAR (test)) foo bar)’ syntax is not
      permitted.
 
  -- Macro: and-let* (bindings...) &rest body
      A combination of LET* and AND, analogous to ‘when-let*’.  If all
      BINDINGS are non-‘nil’ and BODY is ‘nil’, then the result of the
      ‘and-let*’ form will be the last value bound in BINDINGS.
 
      **Please Note:** The implementation provided by Compat does not
      include a bug that was observed with Emacs 26 (see
      <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=31840>).
 
  -- Function: file-local-name filename
      This function returns the _local part_ of FILENAME.  This is the
      part of the file’s name that identifies it on the remote host, and
      is typically obtained by removing from the remote file name the
      parts that specify the remote host and the method of accessing it.
      For example:
 
           (file-local-name "/ssh:USER@HOST:/foo/bar") ⇒
                "/foo/bar"
 
      For a remote FILENAME, this function returns a file name which
      could be used directly as an argument of a remote process (*note
      (elisp)Asynchronous Processes::, and *note (elisp)Synchronous
      Processes::), and as the program to run on the remote host.  If
      FILENAME is local, this function returns it unchanged.
 
      *Note (elisp)Magic File Names::.
 
  -- Function: read-multiple-choice prompt choices
      Ask user a multiple choice question.  PROMPT should be a string
      that will be displayed as the prompt.
 
      CHOICES is an alist where the first element in each entry is a
      character to be entered, the second element is a short name for the
      entry to be displayed while prompting (if there’s room, it might be
      shortened), and the third, optional entry is a longer explanation
      that will be displayed in a help buffer if the user requests more
      help.
 
      See *note Reading One Event: (elisp)Reading One Event.
 
  -- Function: image-property
      Defined in ‘image.el’.
 
      This function can also be used as a generalised variable.
 
  -- Function: file-attribute-type
      Return the field _type_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-link-number
      Return the field _link-number_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-user-id
      Return the field _user-id_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-group-id
      Return the field _group-id_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-access-time
      Return the field _access-time_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-modification-time
      Return the field _modification-time_ as generated by
      ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-status-change-time
      Return the field _modification-time_ as generated by
      ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-size
      Return the field _size_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-modes
      Return the field _modes_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-inode-number
      Return the field _inode-number_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-device-number
      Return the field _device-number_ as generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-attribute-collect attributes &rest attr-names
      Filter the file attributes ATTRIBUTES, as generated by
      ‘file-attributes’, according to ATTR-NAMES.
 
      Valid attribute names for ATTR-NAMES are: type, link-number,
      user-id, group-id, access-time, modification-time,
      status-change-time, size, modes, inode-number and device-number.
 
           (file-attributes ".") ⇒ (t 1 1000 1000 (25329 18215 325481 96000) (25325 15364 530263 840000) (25325 15364 530263 840000) 788 "drwxr-xr-x" t 137819 40)
           (file-attribute-collect (file-attributes ".") 'type 'modes
           'inode-number) ⇒ (t "drwxr-xr-x" 137819)
 
 2.2.2 Extended Definitions
 --------------------------
 
 These functions must be called explicitly via ‘compat-call’, since their
 calling convention or behavior was extended in Emacs 26.1:
 
  -- Function: compat-call make-temp-file prefix &optional dir-flag
           suffix text
      This function creates a temporary file and returns its name.  Emacs
      creates the temporary file’s name by adding to PREFIX some random
      characters that are different in each Emacs job.  The result is
      guaranteed to be a newly created file, containing TEXT if that’s
      given as a string and empty otherwise.  On MS-DOS, this function
      can truncate PREFIX to fit into the 8+3 file-name limits.  If
      PREFIX is a relative file name, it is expanded against
      ‘temporary-file-directory’.
 
      The compatibility version adds support for handling the optional
      argument TEXT.
 
           (make-temp-file "foo")
                ⇒ "/tmp/foo232J6v"
 
      When ‘make-temp-file’ returns, the file has been created and is
      empty.  At that point, you should write the intended contents into
      the file.
 
      If DIR-FLAG is non-‘nil’, ‘make-temp-file’ creates an empty
      directory instead of an empty file.  It returns the file name, not
      the directory name, of that directory.  *Note (elisp)Directory
      Names::.
 
      If SUFFIX is non-‘nil’, ‘make-temp-file’ adds it at the end of the
      file name.
 
      If TEXT is a string, ‘make-temp-file’ inserts it in the file.
 
      To prevent conflicts among different libraries running in the same
      Emacs, each Lisp program that uses ‘make-temp-file’ should have its
      own PREFIX.  The number added to the end of PREFIX distinguishes
      between the same application running in different Emacs jobs.
      Additional added characters permit a large number of distinct names
      even in one Emacs job.
 
  -- Function: compat-call assoc key alist &optional testfn
      This function returns the first association for KEY in ALIST,
      comparing KEY against the alist elements using TESTFN if it is a
      function, and ‘equal’ otherwise (*note (elisp)Equality
      Predicates::).  If TESTFN is a function, it is called with two
      arguments: the CAR of an element from ALIST and KEY.  The function
      returns ‘nil’ if no association in ALIST has a CAR equal to KEY, as
      tested by TESTFN.
 
      *Note (elisp)Association Lists::.
 
      The compatibility version adds support for handling the optional
      argument TESTFN.
 
  -- Function: compat-call line-number-at-pos &optional pos absolute
      This function returns the line number in the current buffer
      corresponding to the buffer position POS.  If POS is ‘nil’ or
      omitted, the current buffer position is used.  If ABSOLUTE is
      ‘nil’, the default, counting starts at ‘(point-min)’, so the value
      refers to the contents of the accessible portion of the
      (potentially narrowed) buffer.  If ABSOLUTE is non-‘nil’, ignore
      any narrowing and return
 
      *Note (elisp)Text Lines::.
 
      The compatibility version adds support for handling the optional
      argument ABSOLUTE.
 
  -- Function: compat-call alist-get key alist &optional default remove
           testfn
      *Note (elisp)Association Lists::.  This function is similar to
      ‘assq’.  It finds the first association ‘(KEY . VALUE)’ by
      comparing KEY with ALIST elements, and, if found, returns the VALUE
      of that association.  If no association is found, the function
      returns DEFAULT.  Comparison of KEY against ALIST elements uses the
      function specified by TESTFN, defaulting to ‘eq’.
 
      *Note (elisp)Association Lists::.
 
      The compatibility version handles the optional argument TESTFN.  It
      can also be used as a *note Generalized Variables:
      (elisp)generalised variable.
 
  -- Function: compat-call string-trim-left string &optional regexp
      Remove the leading text that matches REGEXP from STRING.  REGEXP
      defaults to ‘[ \t\n\r]+’.
 
      *Note (elisp)Creating Strings::.
 
      The compatibility version handles the optional argument REGEXP.
 
  -- Function: compat-call string-trim-right string &optional regexp
      Remove the trailing text that matches REGEXP from STRING.  REGEXP
      defaults to ‘[ \t\n\r]+’.
 
      *Note (elisp)Creating Strings::.
 
      The compatibility version handles the optional argument REGEXP.
 
  -- Function: compat-call string-trim string &optional trim-left
           trim-right
      Remove the leading text that matches TRIM-LEFT and trailing text
      that matches TRIM-RIGHT from STRING.  Both regexps default to ‘[
      \t\n\r]+’.
 
      *Note (elisp)Creating Strings::.
 
      The compatibility version handles the optional arguments TRIM-LEFT
      and TRIM-RIGHT.
 
 2.2.3 Missing Definitions
 -------------------------
 
 Compat does not provide support for the following Lisp features
 implemented in 26.1:
 
    • The function ‘func-arity’.
    • The function ‘secure-hash-algorithms’.
    • The function ‘gnutls-available-p’.
    • Support for records and record functions.
    • The function ‘mapbacktrace’.
    • The function ‘file-name-case-insensitive-p’.
    • The additional elements of ‘parse-partial-sexp’.
    • The function ‘add-variable-watcher’.
    • The function ‘undo-amalgamate-change-group’.
    • The function ‘char-from-name’
    • Signalling errors when ‘length’ or ‘member’ deal with list cycles.
    • The function ‘frame-list-z-order’.
    • The function ‘frame-restack’.
    • All changes related to ‘display-buffer’.
    • The function ‘window-swap-states’.
    • The function ‘string-version-lessp’.
    • The ‘xdg’ library.
    • The ‘svg’ library (published separately as a :core package).
 
 
 File: docXccUUB.info,  Node: Emacs 27.1,  Next: Emacs 28.1,  Prev: Emacs 26.1,  Up: Support
 
 2.3 Emacs 27.1
 ==============
 
 2.3.1 Added Definitions
 -----------------------
 
 The following functions and macros are implemented in Emacs 27.1.  These
 functions are made available by Compat on Emacs versions older than
 27.1.
 
  -- Function: major-mode-suspend
      This function works like ‘fundamental-mode’, in that it kills all
      buffer-local variables, but it also records the major mode in
      effect, so that it could subsequently be restored.  This function
      and ‘major-mode-restore’ (described next) are useful when you need
      to put a buffer under some specialized mode other than the one
      Emacs chooses for it automatically, but would also like to be able
      to switch back to the original mode later.
 
  -- Function: major-mode-restore &optional avoided-modes
      This function restores the major mode recorded by
      ‘major-mode-suspend’.  If no major mode was recorded, this function
      calls ‘normal-mode’, but tries to force it not to choose any modes
      in AVOIDED-MODES, if that argument is non-‘nil’.
 
  -- Function: ring-resize ring size
      Set the size of RING to SIZE.  If the new size is smaller, then the
      oldest items in the ring are discarded.
 
  -- Function: minibuffer-history-value
      Return the value of the minibuffer input history list.  If
      MINIBUFFER-HISTORY-VARIABLE points to a buffer-local variable and
      the minibuffer is active, return the buffer-local value for the
      buffer that was current when the minibuffer was activated."
 
  -- Macro: with-minibuffer-selected-window &rest body
      Execute the forms in BODY from the minibuffer in its original
      window.  When used in a minibuffer window, select the window
      selected just before the minibuffer was activated, and execute the
      forms.
 
  -- Function: read-char-from-minibuffer prompt &optional chars history
      This function uses the minibuffer to read and return a single
      character.  Optionally, it ignores any input that is not a member
      of CHARS, a list of accepted characters.  The HISTORY argument
      specifies the history list symbol to use; if it is omitted or
      ‘nil’, this function doesn’t use the history.
 
      If you bind ‘help-form’ to a non-‘nil’ value while calling
      ‘read-char-from-minibuffer’, then pressing ‘help-char’ causes it to
      evaluate ‘help-form’ and display the result.
 
  -- Function: bignump object
      This predicate tests whether its argument is a large integer, and
      returns ‘t’ if so, ‘nil’ otherwise.  Unlike small integers, large
      integers can be ‘=’ or ‘eql’ even if they are not ‘eq’.
 
  -- Function: fixnump object
      This predicate tests whether its argument is a small integer, and
      returns ‘t’ if so, ‘nil’ otherwise.  Small integers can be compared
      with ‘eq’.
 
  -- Special Form: with-suppressed-warnings warnings body...
      In execution, this is equivalent to ‘(progn BODY...)’, but the
      compiler does not issue warnings for the specified conditions in
      BODY.  WARNINGS is an association list of warning symbols and
      function/variable symbols they apply to.  For instance, if you wish
      to call an obsolete function called ‘foo’, but want to suppress the
      compilation warning, say:
 
           (with-suppressed-warnings ((obsolete foo))
             (foo ...))
 
  -- Function: proper-list-p object
      This function returns the length of OBJECT if it is a proper list,
      ‘nil’ otherwise (*note (elisp)Cons Cells::).  In addition to
      satisfying ‘listp’, a proper list is neither circular nor dotted.
 
           (proper-list-p '(a b c)) ⇒ 3
           (proper-list-p '(a b . c)) ⇒ nil
 
      *Note (elisp)List-related Predicates::.
 
  -- Function: string-distance string1 string2 &optional bytecompare
      This function returns the _Levenshtein distance_ between the source
      string STRING1 and the target string STRING2.  The Levenshtein
      distance is the number of single-character changes—deletions,
      insertions, or replacements—required to transform the source string
      into the target string; it is one possible definition of the _edit
      distance_ between strings.
 
      Letter-case of the strings is significant for the computed
      distance, but their text properties are ignored.  If the optional
      argument BYTECOMPARE is non-‘nil’, the function calculates the
      distance in terms of bytes instead of characters.  The byte-wise
      comparison uses the internal Emacs representation of characters, so
      it will produce inaccurate results for multibyte strings that
      include raw bytes (*note (elisp)Text Representations::); make the
      strings unibyte by encoding them (*note (elisp)Explicit Encoding::)
      if you need accurate results with raw bytes.
 
      *Note (elisp)Text Comparison::.
 
  -- Macro: ignore-errors body...
      This construct executes BODY, ignoring any errors that occur during
      its execution.  If the execution is without error, ‘ignore-errors’
      returns the value of the last form in BODY; otherwise, it returns
      ‘nil’.
 
      Here’s the example at the beginning of this subsection rewritten
      using ‘ignore-errors’:
 
             (ignore-errors (delete-file filename))
 
      *Note (elisp)Handling Errors::.
 
  -- Macro: dolist-with-progress-reporter (var count [result])
           reporter-or-message body...
      This is another convenience macro that works the same way as
      ‘dolist’ does, but also reports loop progress using the functions
      described above.  As in ‘dotimes-with-progress-reporter’,
      ‘reporter-or-message’ can be a progress reporter or a string.  You
      can rewrite the previous example with this macro as follows:
 
           (dolist-with-progress-reporter (k (number-sequence 0 500)) "Collecting
               some mana for Emacs..."  (sit-for 0.01))
 
      *Note (elisp)Progress::.
 
  -- Function: flatten-tree tree
      This function returns a “flattened” copy of TREE, that is, a list
      containing all the non-‘nil’ terminal nodes, or leaves, of the tree
      of cons cells rooted at TREE.  Leaves in the returned list are in
      the same order as in TREE.
 
           (flatten-tree '(1 (2 . 3) nil (4 5 (6)) 7)) ⇒(1 2 3 4 5 6 7)
 
      *Note (elisp)Building Lists::.
 
  -- Function: xor condition1 condition2
      This function returns the boolean exclusive-or of CONDITION1 and
      CONDITION2.  That is, ‘xor’ returns ‘nil’ if either both arguments
      are ‘nil’, or both are non-‘nil’.  Otherwise, it returns the value
      of that argument which is non-‘nil’.
 
      Note that in contrast to ‘or’, both arguments are always evaluated.
 
      *Note (elisp)Combining Conditions::.
 
  -- Variable: regexp-unmatchable
      This variable contains a regexp that is guaranteed not to match any
      string at all.  It is particularly useful as default value for
      variables that may be set to a pattern that actually matches
      something.
 
      *Note (elisp)Regexp Functions::
 
  -- Function: decoded-time-second time
      Return the SECONDS field of a ‘decoded-time’ record TIME.  It can
      also be used as a *note Generalized Variables: (elisp)generalised
      variable.
 
  -- Function: decoded-time-minute time
      Return the MINUTE field of a ‘decoded-time’ record TIME.  It can
      also be used as a *note Generalized Variables: (elisp)generalised
      variable.
 
  -- Function: decoded-time-hour time
      Return the HOUR field of a ‘decoded-time’ record TIME.  It can also
      be used as a *note Generalized Variables: (elisp)generalised
      variable.
 
  -- Function: decoded-time-day time
      Return the DAY field of a ‘decoded-time’ record TIME.  It can also
      be used as a *note Generalized Variables: (elisp)generalised
      variable.
 
  -- Function: decoded-time-month time
      Return the MONTH field of a ‘decoded-time’ record TIME.  It can
      also be used as a *note Generalized Variables: (elisp)generalised
      variable.
 
  -- Function: decoded-time-year time
      Return the YEAR field of a ‘decoded-time’ record TIME.  It can also
      be used as a *note Generalized Variables: (elisp)generalised
      variable.
 
  -- Function: decoded-time-weekday time
      Return the WEEKDAY field of a ‘decoded-time’ record TIME.  It can
      also be used as a *note Generalized Variables: (elisp)generalised
      variable.
 
  -- Function: decoded-time-dst time
      Return the DST (daylight saving time indicator) field of a
      ‘decoded-time’ record TIME.  It can also be used as a *note
      Generalized Variables: (elisp)generalised variable.
 
  -- Function: decoded-time-zone time
      Return the ZONE field of a ‘decoded-time’ record TIME.  It can also
      be used as a *note Generalized Variables: (elisp)generalised
      variable.
 
  -- Function: package-get-version
      Return the version number of the package in which this is used.
 
  -- Function: time-equal-p t1 t2
      This returns ‘t’ if the two time values T1 and T2 are equal.
 
      *Note (elisp)Time Calculations::.
 
  -- Function: date-days-in-month year month
      Return the number of days in MONTH in YEAR.  For instance, February
      2020 has 29 days.
 
      *Note (elisp)Time Calculations::.  This function requires the
      ‘time-date’ feature to be loaded.
 
  -- Function: date-ordinal-to-time year ordinal
      Convert a YEAR/ORDINAL to the equivalent decoded-time structure.
      ORDINAL is the number of days since the start of the year, with
      January 1st being 1.
 
      *Note (elisp)Time Calculations::.  This function requires the
      ‘time-date’ feature to be loaded.
 
  -- User Option: exec-path
      The value of this variable is a list of directories to search for
      programs to run in subprocesses.  Each element is either the name
      of a directory (i.e., a string), or ‘nil’, which stands for the
      default directory (which is the value of ‘default-directory’).
      *Note executable-find: (elisp)Locating Files, for the details of
      this search.
 
      The value of ‘exec-path’ is used by ‘call-process’ and
      ‘start-process’ when the PROGRAM argument is not an absolute file
      name.
 
      Generally, you should not modify ‘exec-path’ directly.  Instead,
      ensure that your ‘PATH’ environment variable is set appropriately
      before starting Emacs.  Trying to modify ‘exec-path’ independently
      of ‘PATH’ can lead to confusing results.
 
      *Note (elisp)Subprocess Creation::.
 
  -- Function: provided-mode-derived-p mode &rest modes
      This function returns non-‘nil’ if MODE is derived from any of the
      major modes given by the symbols MODES.
 
  -- Function: file-size-human-readable-iec size
      Human-readable string for SIZE bytes, using IEC prefixes.
 
  -- Function: make-empty-file filename &optional parents
      This function creates an empty file named FILENAME.  As
      ‘make-directory’, this function creates parent directories if
      PARENTS is non-‘nil’.  If FILENAME already exists, this function
      signals an error.
 
  -- Function: text-property-search-forward prop &optional value
           predicate not-current
      Search for the next region that has text property PROP set to VALUE
      according to PREDICATE.
 
      This function is modeled after ‘search-forward’ and friends in that
      it moves point, but it returns a structure that describes the match
      instead of returning it in ‘match-beginning’ and friends.
 
      If the text property can’t be found, the function returns ‘nil’.
      If it’s found, point is placed at the end of the region that has
      this text property match, and a ‘prop-match’ structure is returned.
 
      PREDICATE can either be ‘t’ (which is a synonym for ‘equal’), ‘nil’
      (which means “not equal”), or a predicate that will be called with
      two parameters: The first is VALUE, and the second is the value of
      the text property we’re inspecting.
 
      If NOT-CURRENT, if point is in a region where we have a match, then
      skip past that and find the next instance instead.
 
      The ‘prop-match’ structure has the following accessors:
      ‘prop-match-beginning’ (the start of the match), ‘prop-match-end’
      (the end of the match), and ‘prop-match-value’ (the value of
      PROPERTY at the start of the match).
 
      In the examples below, imagine that you’re in a buffer that looks
      like this:
 
           This is a bold and here's bolditalic and this is the end.
 
      That is, the “bold” words are the ‘bold’ face, and the “italic”
      word is in the ‘italic’ face.
 
      With point at the start:
 
           (while (setq match (text-property-search-forward 'face 'bold t))
             (push (buffer-substring (prop-match-beginning match)
                                     (prop-match-end match))
                   words))
 
      This will pick out all the words that use the ‘bold’ face.
 
           (while (setq match (text-property-search-forward 'face nil t))
             (push (buffer-substring (prop-match-beginning match)
                                     (prop-match-end match))
                   words))
 
      This will pick out all the bits that have no face properties, which
      will result in the list ‘("This is a " "and here's " "and this is
      the end")’ (only reversed, since we used ‘push’).
 
           (while (setq match (text-property-search-forward 'face nil nil))
             (push (buffer-substring (prop-match-beginning match)
                                     (prop-match-end match))
                   words))
 
      This will pick out all the regions where ‘face’ is set to
      something, but this is split up into where the properties change,
      so the result here will be ‘("bold" "bold" "italic")’.
 
      For a more realistic example where you might use this, consider
      that you have a buffer where certain sections represent URLs, and
      these are tagged with ‘shr-url’.
 
           (while (setq match (text-property-search-forward 'shr-url nil nil))
             (push (prop-match-value match) urls))
 
      This will give you a list of all those URLs.
 
      *Note (Property Search)elisp::.
 
  -- Function: text-property-search-backward prop &optional value
           predicate not-current
      This is just like ‘text-property-search-forward’, but searches
      backward instead.  Point is placed at the beginning of the matched
      region instead of the end, though.
 
      *Note (Property Search)elisp::.
 
 2.3.2 Extended Definitions
 --------------------------
 
 These functions must be called explicitly via ‘compat-call’, since their
 calling convention or behavior was extended in Emacs 27.1:
 
  -- Function: compat-call recenter &optional count redisplay
      This function scrolls the text in the selected window so that point
      is displayed at a specified vertical position within the window.
      It does not move point with respect to the text.
 
      *Note (elisp)Textual Scrolling::.
 
      This compatibility version adds support for the optional argument
      REDISPLAY.
 
  -- Function: compat-call lookup-key keymap key &optional
           accept-defaults
      This function returns the definition of KEY in KEYMAP.  If the
      string or vector KEY is not a valid key sequence according to the
      prefix keys specified in KEYMAP, it must be too long and have extra
      events at the end that do not fit into a single key sequence.  Then
      the value is a number, the number of events at the front of KEY
      that compose a complete key.
 
      *Note (elisp)Low-Level Key Binding::.
 
      This compatibility version allows for KEYMAP to be a list of
      keymaps, instead of just a singular keymap.
 
  -- Macro: compat-call setq-local &rest pairs
      PAIRS is a list of variable and value pairs.  This macro creates a
      buffer-local binding in the current buffer for each of the
      variables, and gives them a buffer-local value.  It is equivalent
      to calling ‘make-local-variable’ followed by ‘setq’ for each of the
      variables.  The variables should be unquoted symbols.
 
           (setq-local var1 "value1"
                       var2 "value2")
 
      *Note (elisp)Creating Buffer-Local::.
 
      This compatibility version allows for more than one variable to be
      set at once, as can be done with ‘setq’.
 
  -- Function: compat-call regexp-opt strings &optional paren
      This function returns an efficient regular expression that will
      match any of the strings in the list STRINGS.  This is useful when
      you need to make matching or searching as fast as possible—for
      example, for Font Lock mode.
 
      *Note (elisp)Regexp Functions::.
 
      The compatibility version of this functions handles the case where
      STRINGS in an empty list.  In that case, a regular expression is
      generated that never matches anything (see ‘regexp-unmatchable’).
 
  -- Function: compat-call file-size-human-readable file-size &optional
           flavor space unit
      Return a string with a human readable representation of FILE-SIZE.
 
      The optional second argument FLAVOR controls the units and the
      display format.  If FLAVOR is...
 
         • ‘si’, each kilobyte is 1000 bytes and the produced suffixes
           are ‘k’, ‘M’, ‘G’, ‘T’, etc.
         • ‘iec’, each kilobyte is 1024 bytes and the produced suffixes
           are ‘KiB’, ‘MiB’, ‘GiB’, ‘TiB’, etc.
         • ‘nil’ or omitted, each kilobyte is 1024 bytes and the produced
           suffixes are ‘k’, ‘M’, ‘G’, ‘T’, etc.
 
      The compatibility version handles the optional third (SPACE) and
      forth (UNIT) arguments.  The argument SPACE can be a string that is
      placed between the number and the unit.  The argument UNIT
      determines the unit to use.  By default it will be an empty string,
      unless FLAVOR is ‘iec’, in which case it will be ‘B’.
 
  -- Function: compat-call assoc-delete-all key alist &optional test
      This function is like ‘assq-delete-all’ except that it accepts an
      optional argument TEST, a predicate function to compare the keys in
      ALIST.  If omitted or ‘nil’, TEST defaults to ‘equal’.  As
      ‘assq-delete-all’, this function often modifies the original list
      structure of ALIST.
 
      *Note (elisp)Association Lists::.
 
      This compatibility version handles the optional third (TESTFN)
      argument.
 
  -- Function: compat-call executable-find program &optional remote
      This function searches for the executable file of the named PROGRAM
      and returns the absolute file name of the executable, including its
      file-name extensions, if any.  It returns ‘nil’ if the file is not
      found.  The function searches in all the directories in
      ‘exec-path’, and tries all the file-name extensions in
      ‘exec-suffixes’ (*note (elisp)Subprocess Creation::).
 
      If REMOTE is non-‘nil’, and ‘default-directory’ is a remote
      directory, PROGRAM is searched on the respective remote host.
 
      *Note (elisp)Locating Files::.
 
      This compatibility version adds support to handle the optional
      second (REMOTE) argument.
 
 2.3.3 Missing Definitions
 -------------------------
 
 Compat does not provide support for the following Lisp features
 implemented in 27.1:
 
    • The functions ‘base64url-encode-*’.
    • The function ‘decoded-time-add’.
    • The function ‘decoded-time-set-defaults’.
    • The function ‘time-convert’.
    • The macro ‘benchmark-progn’.
    • Support for ‘condition-case’ to handle t.
    • The function ‘file-system-info’.
    • The function ‘group-name’.
    • The function ‘face-extend-p’ and ‘set-face-extend’.
    • Additional ‘format-spec’ modifiers.
    • Support for additional body forms for
      ‘define-globalized-minor-mode’.
    • The macro ‘with-connection-local-variables’ and related
      functionality.
    • The ‘iso8601’ library.
    • The ‘exif’ library.
    • The ‘image-converter’ library.
 
 
 File: docXccUUB.info,  Node: Emacs 28.1,  Next: Emacs 29.1,  Prev: Emacs 27.1,  Up: Support
 
 2.4 Emacs 28.1
 ==============
 
 2.4.1 Added Definitions
 -----------------------
 
 The following functions and macros are implemented in Emacs 28.1.  These
 functions are made available by Compat on Emacs versions older than
 28.1.
 
    The ‘defcustom’ type ‘natnum’ introduced in Emacs 28.1 is made
 available by Compat.
 
  -- Function: process-lines-ignore-status program &rest args
      This function is just like ‘process-lines’, but does not signal an
      error if PROGRAM exits with a non-zero exit status.
 
  -- Function: process-lines-handling-status program status-handler &rest
           args
      Execute PROGRAM with ARGS, returning its output as a list of lines.
      If STATUS-HANDLER is non-nil, it must be a function with one
      argument, which will be called with the exit status of the program
      before the output is collected.  If STATUS-HANDLER is nil, an error
      is signaled if the program returns with a non-zero exit status.
 
  -- Function: text-quoting-style
      You should not read the value of the variable ‘text-quoting-style’
      directly.  Instead, use this function with the same name to
      dynamically compute the correct quoting style on the current
      terminal in the ‘nil’ case described above.
 
  -- Function: string-search needle haystack &optional start-pos
      Return the position of the first instance of NEEDLE in HAYSTACK,
      both of which are strings.  If START-POS is non-‘nil’, start
      searching from that position in NEEDLE.  Return ‘nil’ if no match
      was found.  This function only considers the characters in the
      strings when doing the comparison; text properties are ignored.
      Matching is always case-sensitive.
 
  -- Function: length= sequence length
      Return non-‘nil’ if the length of SEQUENCE is equal to LENGTH.
 
  -- Function: length< sequence length
      Return non-‘nil’ if SEQUENCE is shorter than LENGTH.  This may be
      more efficient than computing the length of SEQUENCE if SEQUENCE is
      a long list.
 
  -- Function: length> sequence length
      Return non-‘nil’ if SEQUENCE is longer than LENGTH.
 
  -- Function: file-name-concat directory &rest components
      Concatenate COMPONENTS to DIRECTORY, inserting a slash before the
      components if DIRECTORY or the preceding component didn’t end with
      a slash.
 
           (file-name-concat "/tmp" "foo") ⇒ "/tmp/foo"
 
      A DIRECTORY or components that are ‘nil’ or the empty string are
      ignored—they are filtered out first and do not affect the results
      in any way.
 
      This is almost the same as using ‘concat’, but DIRNAME (and the
      non-final components) may or may not end with slash characters, and
      this function will not double those characters.
 
  -- Function: garbage-collect-maybe factor
      Suggest to run garbage collection, if _enough_ data has been
      allocated.  This is determined by the positive numerical argument
      FACTOR, that would proportionally increase the likelihood of
      garbage collection taking place.
 
      This compatibility function does nothing and ignores any
      suggestion.
 
  -- Function: string-replace from-string to-string in-string
      This function replaces all occurrences of FROM-STRING with
      TO-STRING in IN-STRING and returns the result.  It may return one
      of its arguments unchanged, a constant string or a new string.
      Case is significant, and text properties are ignored.
 
  -- Function: always &rest arguments
      This function ignores any ARGUMENTS and returns ‘t’.
 
      *Note (elisp)Calling Functions::.
 
  -- Function: make-separator-line &optional length
      Make a string appropriate for usage as a visual separator line.  If
      LENGTH is nil, use the window width.
 
  -- Function: insert-into-buffer to-buffer &optional start end
      This is like ‘insert-buffer-substring’, but works in the opposite
      direction: The text is copied from the current buffer into
      TO-BUFFER.  The block of text is copied to the current point in
      TO-BUFFER, and point (in that buffer) is advanced to after the end
      of the copied text.  Is ‘start’/‘end’ is ‘nil’, the entire text in
      the current buffer is copied over.
 
      *Note (elisp)Insertion::.
 
  -- Function: replace-string-in-region regexp replacement &optional
           start end
      This function replaces all the occurrences of REGEXP with
      REPLACEMENT in the region of buffer text between START and END;
      START defaults to position of point, and END defaults to the last
      accessible position of the buffer.  The search for REGEXP is
      case-sensitive, and REPLACEMENT is inserted without changing its
      letter-case.  The REPLACEMENT string can use the same special
      elements starting with ‘\’ as ‘replace-match’ does.  The function
      returns the number of replaced occurrences, or ‘nil’ if REGEXP is
      not found.  The function preserves the position of point.
 
           (replace-regexp-in-region "foo[ \t]+bar" "foobar")
      *Note (elisp)Search and Replace::.
 
  -- Function: replace-regexp-in-string string replacement &optional
           start end
      This function works similarly to ‘replace-regexp-in-region’, but
      searches for, and replaces, literal STRINGs instead of regular
      expressions.
 
      *Note (elisp)Search and Replace::.
 
  -- Function: buffer-local-boundp variable buffer
      This returns non-‘nil’ if there’s either a buffer-local binding of
      VARIABLE (a symbol) in buffer BUFFER, or VARIABLE has a global
      binding.
 
      *Note (elisp)Creating Buffer-Local::.
 
  -- Macro: with-existing-directory body...
      This macro ensures that ‘default-directory’ is bound to an existing
      directory before executing BODY.  If ‘default-directory’ already
      exists, that’s preferred, and otherwise some other directory is
      used.  This macro can be useful, for instance, when calling an
      external command that requires that it’s running in a directory
      that exists.  The chosen directory is not guaranteed to be
      writable.
 
      *Note (elisp)Testing Accessibility::.
 
  -- Macro: dlet (bindings...) forms...
      This special form is like ‘let’, but it binds all variables
      dynamically.  This is rarely useful—you usually want to bind normal
      variables lexically, and special variables (i.e., variables that
      are defined with ‘defvar’) dynamically, and this is what ‘let’
      does.
 
      ‘dlet’ can be useful when interfacing with old code that assumes
      that certain variables are dynamically bound (*note (elisp)Dynamic
      Binding::), but it’s impractical to ‘defvar’ these variables.
      ‘dlet’ will temporarily make the bound variables special, execute
      the forms, and then make the variables non-special again.
 
      *Note (elisp)Local Variables::.
 
  -- Function: ensure-list object
      This function returns OBJECT as a list.  If OBJECT is already a
      list, the function returns it; otherwise, the function returns a
      one-element list containing OBJECT.
 
      This is usually useful if you have a variable that may or may not
      be a list, and you can then say, for instance:
 
           (dolist (elem (ensure-list foo))
             (princ elem))
 
      *Note (elisp)Building Lists::.
 
  -- Function: string-clean-whitespace string
      Clean up the whitespace in STRING by collapsing stretches of
      whitespace to a single space character, as well as removing all
      whitespace from the start and the end of STRING.
 
      *Note (elisp)Creating Strings::.
 
  -- Function: string-fill string length
      Attempt to Word-wrap STRING so that no lines are longer than
      LENGTH.  Filling is done on whitespace boundaries only.  If there
      are individual words that are longer than LENGTH, these will not be
      shortened.
 
      *Note (elisp)Creating Strings::.
 
  -- Function: string-lines string &optional omit-nulls
      Split STRING into a list of strings on newline boundaries.  If the
      optional argument OMIT-NULLS is non-‘nil’, remove empty lines from
      the results.  Note that this function returns trailing newlines on
      Emacs 28, use ‘compat-call string-lines’ instead if you want
      consistent behavior.
 
  -- Function: string-pad string length &optional padding start
      Pad STRING to be of the given LENGTH using PADDING as the padding
      character.  PADDING defaults to the space character.  If STRING is
      longer than LENGTH, no padding is done.  If START is ‘nil’ or
      omitted, the padding is appended to the characters of STRING, and
      if it’s non-‘nil’, the padding is prepended to STRING’s characters.
 
      *Note (elisp)Creating Strings::.
 
  -- Function: string-chop-newline string
      Remove the final newline, if any, from STRING.
 
      *Note (elisp)Creating Strings::.
 
  -- Macro: named-let name bindings &rest body
      This special form is a looping construct inspired from the Scheme
      language.  It is similar to ‘let’: It binds the variables in
      BINDINGS, and then evaluates BODY.  However, ‘named-let’ also binds
      NAME to a local function whose formal arguments are the variables
      in BINDINGS and whose body is BODY.  This allows BODY to call
      itself recursively by calling NAME, where the arguments passed to
      NAME are used as the new values of the bound variables in the
      recursive invocation.
 
      Recursive calls to NAME that occur in _tail positions_ in BODY are
      guaranteed to be optimized as _tail calls_, which means that they
      will not consume any additional stack space no matter how deeply
      the recursion runs.  Such recursive calls will effectively jump to
      the top of the loop with new values for the variables.
 
      *Note (elisp)Local Variables::.
 
  -- Function: file-name-with-extension filename extension
      This function returns FILENAME with its extension set to EXTENSION.
      A single leading dot in the EXTENSION will be stripped if there is
      one.  For example:
 
           (file-name-with-extension "file" "el")
                ⇒ "file.el"
           (file-name-with-extension "file" ".el")
                ⇒ "file.el"
           (file-name-with-extension "file.c" "el")
                ⇒ "file.el"
 
      Note that this function will error if FILENAME or EXTENSION are
      empty, or if the FILENAME is shaped like a directory (i.e., if
      ‘directory-name-p’ returns non-‘nil’).
 
      *Note File Name Components: (elisp)File Name Components.
 
  -- Function: directory-empty-p directory
      This utility function returns ‘t’ if given DIRECTORY is an
      accessible directory and it does not contain any files, i.e., is an
      empty directory.  It will ignore ‘.’ and ‘..’ on systems that
      return them as files in a directory.
 
      Symbolic links to directories count as directories.  See
      FILE-SYMLINK-P to distinguish symlinks.
 
      *Note (elisp)Contents of Directories::.
 
  -- Function: format-prompt prompt default &rest format-args
      Format PROMPT with default value DEFAULT according to the
      ‘minibuffer-default-prompt-format’ variable.
 
      ‘minibuffer-default-prompt-format’ is a format string (defaulting
      to ‘" (default %s)"’ that says how the “default” bit in prompts
      like ‘"Local filename (default somefile): "’ are to be formatted.
 
      To allow the users to customize how this is displayed, code that
      prompts the user for a value (and has a default) should look
      something along the lines of this code snippet:
 
           (read-file-name
            (format-prompt "Local filename" file)
            nil file)
 
      If FORMAT-ARGS is ‘nil’, PROMPT is used as a literal string.  If
      FORMAT-ARGS is non-‘nil’, PROMPT is used as a format control
      string, and PROMPT and FORMAT-ARGS are passed to ‘format’ (*note
      (elisp)Formatting Strings::).
 
      ‘minibuffer-default-prompt-format’ can be ‘""’, in which case no
      default values are displayed.
 
      If DEFAULT is ‘nil’, there is no default value, and therefore no
      “default value” string is included in the result value.  If DEFAULT
      is a non-‘nil’ list, the first element of the list is used in the
      prompt.
 
      *Note (elisp)Text from Minibuffer::.
 
  -- Function: thing-at-mouse event thing &optional no-properties
      Mouse-EVENT equivalent of ‘thing-at-point’.  THING can be ‘symbol’,
      ‘list’, ‘sexp’, ‘filename’, ‘url’, ... among other things.
 
      When NO-PROPERTIES has a non-‘nil’ value, any text properties that
      might have been present in the buffer are stripped away.
 
  -- Function: bounds-of-thing-at-mouse event thing
      Determine start and end locations for THING at mouse click given by
      EVENT.  Like ‘bounds-of-thing-at-point’, but tries to use the
      position in EVENT where the mouse button is clicked to find the
      thing nearby.
 
  -- Function: mark-thing-at-mouse click thing
      Activate the region around THING found near the mouse CLICK.
 
  -- Function: macroexp-file-name
      Return the name of the file in which the code is currently being
      evaluated, or ‘nil’ if it cannot be determined.
 
  -- Function: macroexp-warn-and-return msg form &optional category
           compile-only arg
      Return code equivalent to ‘form’ labeled with warning ‘msg’.
 
  -- Macro: with-environment-variables variables body...
      This macro sets the environment variables according to VARIABLES
      temporarily when executing BODY.  The previous values are restored
      when the form finishes.  The argument VARIABLES should be a list of
      pairs of strings of the form ‘(VAR VALUE)’, where VAR is the name
      of the environment variable and VALUE is that variable’s value.
 
           (with-environment-variables (("LANG" "C")
                                        ("LANGUAGE" "en_US:en"))
             (call-process "ls" nil t))
 
      *Note System Environment: (elisp)System Environment.
 
  -- Function: color-dark-p rgb
      Whether RGB is more readable against white than black.  RGB is a
      3-element list (R G B), each component in the range [0,1].  This
      predicate can be used both for determining a suitable (black or
      white) contrast color with RGB as background and as foreground.
 
  -- Function: color-values-from-color-spec spec
      Convert the textual color specification SPEC to a color triple
      ‘(RED GREEN blue)’.  Each of RED, GREEN and ‘blue’ is a integer
      value between 0 and 65535.
 
      The specification SPEC can be one of the following
         • ‘#RGB’, where R, G and B are hex numbers of equal length, 1-4
           digits each.
         • ‘rgb:R/G/B’, where R, G, and B are hex numbers, 1-4 digits
           each.
         • ‘rgbi:R/G/B’, where R, G and B are floating-point numbers in
           [0,1].
 
  -- Function: file-modes-number-to-symbolic modes
      This function converts a numeric file mode specification in MODES
      into the equivalent symbolic form.
 
      *Note Changing Files: (elisp)Changing Files.
 
  -- Function: file-backup-file-names filename
      This function returns a list of all the backup file names for
      FILENAME, or ‘nil’ if there are none.  The files are sorted by
      modification time, descending, so that the most recent files are
      first.
 
      *Note (elisp)Backup Names::.
 
  -- Function: make-lock-file-name filename
      Return a string containing a lock file name for FILENAME, obeying
      ‘lock-file-name-transforms’.
 
  -- Function: decoded-time-period time
      Interpret TIME as a period and return its length in seconds.  For
      computational purposes, years are 365 days long and months are 30
      days long.
 
  -- Function: subr-primitive-p object
      Return ‘t’ if OBJECT is a primitive, built-in function.  On systems
      with native compilation ‘subrp’ does not distinguish between
      built-in functions and functions that have been compiled.  If
      native compilation is not available, this function behaves
      identically to ‘subrp’.
 
  -- Function: subr-native-elisp-p object
      Return ‘t’ if OBJECT if the object is native compiled lisp.  If
      native compilation is not available, this function always returns
      ‘nil’.
 
  -- Function: native-comp-available-p
      This function returns non-‘nil’ if the running Emacs process has
      the native-compilation support compiled into it.  On systems that
      load ‘libgccjit’ dynamically, it also makes sure that library is
      available and can be loaded.  Lisp programs that need to know up
      front whether native-compilation is available should use this
      predicate.
 
  -- Macro: with-window-non-dedicated window &rest body
      Evaluate BODY with WINDOW temporarily made non-dedicated.  If
      WINDOW is nil, use the selected window.  Return the value of the
      last form in BODY.
 
 2.4.2 Extended Definitions
 --------------------------
 
 These functions must be called explicitly via ‘compat-call’, since their
 calling convention or behavior was extended in Emacs 28.1:
 
  -- Function: compat-call string-width string &optional from to
      This function returns the width in columns of the string STRING, if
      it were displayed in the current buffer and the selected window.
      Optional arguments FROM and TO specify the substring of STRING to
      consider, and are interpreted as in ‘substring’ (*note
      (elisp)Creating Strings::).
 
      The return value is an approximation: it only considers the values
      returned by ‘char-width’ for the constituent characters, always
      takes a tab character as taking ‘tab-width’ columns, ignores
      display properties and fonts, etc.
 
      *Note (elisp)Size of Displayed Text::.
 
      This compatibility version handles the optional arguments FROM and
      TO.
 
  -- Function: compat-call count-windows
      Return the number of live windows on the selected frame.
 
      The optional argument MINIBUF specifies whether the minibuffer
      window is included in the count.
 
      If ALL-FRAMES is non-‘nil’, count the windows in all frames instead
      just the selected frame.
 
      This compatibility version handles the optional argument
      ALL-FRAMES.
 
 2.4.3 Missing Definitions
 -------------------------
 
 Compat does not provide support for the following Lisp features
 implemented in 28.1:
 
    • Support for ‘interactive’ or ‘declare’ to list applicable modes.
    • Support for ‘:interactive’ argument to ‘define-minor-mode’ and
      ‘define-derived-mode’.
    • Support for ‘:predicate’ argument to
      ‘define-globalized-minor-mode’.
    • Support for the ‘:success’ handler of ‘condition-case’.
    • The function ‘benchmark-call’.
    • Additional Edebug keywords.
    • The libjansson JSON APIs, e.g., ‘json-parse-string’.
    • The macro ‘pcase-setq’.
    • The function ‘custom-add-choice’.
    • The functions ‘dom-print’ and ‘dom-remove-attribute’.
    • The function ‘dns-query-asynchronous’.
    • The function ‘get-locale-names’.
    • The functions ‘mail-header-parse-addresses-lax’ and
      ‘mail-header-parse-address-lax’.
    • The function ‘num-processors’.
    • The function ‘object-intervals’.
    • The function ‘require-theme’.
    • The function ‘syntax-class-to-char’.
    • The function ‘path-separator’.
    • The function ‘null-device’.
    • The function ‘macroexp-compiling-p’.
    • The function ‘split-string-shell-command’.
    • The function ‘string-limit’.
    • The functions ‘innermost-minibuffer-p’ and
      ‘minibuffer-innermost-command-loop-p’.
    • The function ‘max-mini-window-lines’.
    • The function ‘lock-file’ and ‘unlock-file’.
    • The ‘multisession’ library.
 
 
 File: docXccUUB.info,  Node: Emacs 29.1,  Prev: Emacs 28.1,  Up: Support
 
 2.5 Emacs 29.1
 ==============
 
 2.5.1 Added Definitions
 -----------------------
 
 The following functions and macros are implemented in Emacs 29.1.  These
 functions are made available by Compat on Emacs versions older than
 29.1.  Note that due to upstream changes, it might happen that there
 will be the need for changes, so use these functions with care.
 
    The ‘defcustom’ type ‘key’ introduced in Emacs 29.1 is made available
 by Compat.
 
  -- Variable: lisp-directory
      This variable holds a string naming the directory which holds
      Emacs’s own ‘*.el’ and ‘*.elc’ files.  This is usually the place
      where those files are located in the Emacs installation tree,
      unless Emacs is run from its build directory in which case it
      points to the ‘lisp’ subdirectory in the source directory from
      which Emacs was built.
 
  -- Function: count-sentences start end
      Count sentences in current buffer from START to END.
 
  -- Function: readablep object
      This predicate says whether OBJECT has “readable syntax”, i.e., it
      can be written out and then read back by the Emacs Lisp reader.  If
      it can’t, this function returns ‘nil’; if it can, this function
      returns a printed representation (via ‘prin1’).
 
  -- Function: substitute-quotes string
      This function works like ‘substitute-command-keys’, but only
      replaces quote characters.
 
  -- Function: get-scratch-buffer-create
      Return the *scratch* buffer, creating a new one if needed.
 
  -- Function: use-region-noncontiguous-p
      Return non-nil for a non-contiguous region if ‘use-region-p’.
 
  -- Function: use-region-end
      Return the end of the region if ‘use-region-p’.
 
  -- Function: use-region-beginning
      Return the start of the region if ‘use-region-p’.
 
  -- Macro: buffer-local-set-state variable value...
      Minor modes often set buffer-local variables that affect some
      features in Emacs.  When a minor mode is switched off, the mode is
      expected to restore the previous state of these variables.  This
      convenience macro helps with doing that: It works much like
      ‘setq-local’, but returns an object that can be used to restore
      these values back to their previous values/states (using the
      companion function ‘buffer-local-restore-state’).
 
  -- Function: delete-line
      Delete the current line.
 
  -- Function: list-of-strings-p object
      Return ‘t’ if OBJECT is ‘nil’ or a list of strings.
 
  -- Function: plistp object
      Non-nil if and only if OBJECT is a valid plist.
 
  -- Macro: with-memoization PLACE CODE...
      This macro provides a simple way to do memoization.  CODE is
      evaluated and then stashed in PLACE.  If PLACE’s value is
      non-‘nil’, return that value instead of evaluating CODE.
 
  -- Special Form: with-restriction start end [:label label] body
      This special form saves the current bounds of the accessible
      portion of the buffer, sets the accessible portion to start at
      START and end at END, evaluates the BODY forms, and restores the
      saved bounds.  In that case it is equivalent to
 
           (save-restriction
             (narrow-to-region start end)
             body)
 
      When the optional argument LABEL, a symbol, is present, the
      narrowing is “labeled”.  A labeled narrowing differs from a
      non-labeled one in several ways:
 
         • During the evaluation of the BODY form, ‘narrow-to-region’ and
           ‘widen’ can be used only within the START and END limits.
 
         • To lift the restriction introduced by ‘with-restriction’ and
           gain access to other portions of the buffer, use
           ‘without-restriction’ with the same LABEL argument.  (Another
           way to gain access to other portions of the buffer is to use
           an indirect buffer (*note (elisp)Indirect Buffers::).)
 
         • Labeled narrowings can be nested.
 
         • Labeled narrowings can only be used in Lisp programs: they are
           never visible on display, and never interfere with narrowings
           set by the user.
 
      If you use ‘with-restriction’ with the optional LABEL argument, we
      recommend documenting the LABEL in the doc strings of the functions
      which use it, so that other Lisp programs your code calls could
      lift the labeled narrowing if and when it needs.
 
  -- Special Form: without-restriction [:label label] body
      This special form saves the current bounds of the accessible
      portion of the buffer, widens the buffer, evaluates the BODY forms,
      and restores the saved bounds.  In that case it is equivalent to
 
           (save-restriction
             (widen)
             body)
 
      When the optional argument LABEL is present, the narrowing set by
      ‘with-restriction’ with the same LABEL argument is lifted.
 
  -- Function: pos-bol &optional count
      Like ‘line-beginning-position’, but ignores fields (and is more
      efficient).
 
  -- Function: pos-eol &optional count
      Like ‘line-end-position’, but ignores fields (and is more
      efficient).
 
  -- Function: char-uppercase-p char
      Return non-‘nil’ if CHAR is an uppercase character according to
      Unicode.
 
  -- Macro: with-delayed-message (timeout message) body...
      Sometimes it’s unclear whether an operation will take a long time
      to execute or not, or it can be inconvenient to implement a
      progress reporter.  This macro can be used in those situations.
 
           (with-delayed-message (2 (format "Gathering data for %s" entry))
             (setq data (gather-data entry)))
 
      In this example, if the body takes more than two seconds to
      execute, the message will be displayed.  If it takes a shorter time
      than that, the message won’t be displayed.  In either case, the
      body is evaluated as normally, and the return value of the final
      element in the body is the return value of the macro.
 
      The MESSAGE element is evaluated before BODY, and is always
      evaluated, whether the message is displayed or not.
 
  -- Function: funcall-with-delayed-message timeout message function
      Like ‘funcall’, but display MESSAGE if FUNCTION takes longer than
      TIMEOUT.  TIMEOUT is a number of seconds, and can be an integer or
      a floating point number.
 
      If FUNCTION takes less time to execute than TIMEOUT seconds,
      MESSAGE is not displayed.
 
  -- Function: buttonize string callback &optional data help-echo
      Sometimes it’s more convenient to make a string into a button
      without inserting it into a buffer immediately, for instance when
      creating data structures that may then, later, be inserted into a
      buffer.  This function makes STRING into such a string, and
      CALLBACK will be called when the user clicks on the button.  The
      optional DATA parameter will be used as the parameter when CALLBACK
      is called.  If ‘nil’, the button is used as the parameter instead.
 
  -- Function: buttonize-region start end callback &optional data
           help-echo
      Make the region between START and END into a button.  When clicked,
      CALLBACK will be called with the DATA as the function argument.  If
      DATA isn’t present (or is nil), the button itself will be used
      instead as the function argument.  If HELP-ECHO, use that as the
      help-echo property.
 
  -- Function: get-display-property position prop &optional object
           properties
      This convenience function can be used to get a specific display
      property, no matter whether the ‘display’ property is a vector, a
      list or a simple property.  This is like ‘get-text-property’ (*note
      Examining Properties: (elisp)Examining Properties.), but works on
      the ‘display’ property only.
 
      POSITION is the position in the buffer or string to examine, and
      PROP is the ‘display’ property to return.  The optional OBJECT
      argument should be either a string or a buffer, and defaults to the
      current buffer.  If the optional PROPERTIES argument is non-‘nil’,
      it should be a ‘display’ property, and in that case, POSITION and
      OBJECT are ignored.  (This can be useful if you’ve already gotten
      the ‘display’ property with ‘get-char-property’, for instance
      (*note Examining Properties: (elisp)Examining Properties.).
 
  -- Function: add-display-text-property start end prop value &optional
           object
      Add display property PROP with VALUE to the text from START to END.
      If any text in the region has a non-nil ‘display’ property, those
      properties are retained.
 
      If OBJECT is non-‘nil’, it should be a string or a buffer.  If
      ‘nil’, this defaults to the current buffer.
 
  -- Function: take n list
      This function returns the N first elements of LIST.  Essentially,
      it returns the part of LIST that ‘nthcdr’ skips.
 
      ‘take’ returns LIST if shorter than N elements; it returns ‘nil’ if
      N is zero or negative.
 
           (take 3 '(a b c d))
                ⇒ (a b c)
           (take 10 '(a b c d))
                ⇒ (a b c d)
           (take 0 '(a b c d))
                ⇒ nil
 
  -- Function: ntake n list
      This is a version of ‘take’ that works by destructively modifying
      the list structure of the argument.  That makes it faster, but the
      original value of LIST may be lost.
 
      ‘ntake’ returns LIST unmodified if shorter than N elements; it
      returns ‘nil’ if N is zero or negative.  Otherwise, it returns LIST
      truncated to its first N elements.
 
      This means that it is usually a good idea to use the return value
      and not just rely on the truncation effect unless N is known to be
      positive.
 
  -- Function: compiled-function-p object
      This function returns ‘t’ if OBJECT is a function object that is
      not in the form of ELisp source code but something like machine
      code or byte code instead.  More specifically it returns ‘t’ if the
      function is built-in, or byte-compiled, or natively-compiled, or a
      function loaded from a dynamic module.
 
  -- Function: function-alias-p object &optional noerror
      Checks whether OBJECT is a function alias.  If it is, it returns a
      list of symbols representing the function alias chain, else ‘nil’.
      For instance, if ‘a’ is an alias for ‘b’, and ‘b’ is an alias for
      ‘c’:
 
           (function-alias-p 'a)
               ⇒ (b c)
 
      If there’s a loop in the definitions, an error will be signalled.
      If NOERROR is non-‘nil’, the non-looping parts of the chain is
      returned instead.
 
  -- Function: string-equal-ignore-case string1 string2
      ‘string-equal-ignore-case’ compares strings ignoring case
      differences, like ‘char-equal’ when ‘case-fold-search’ is ‘t’.
 
      *Note (elisp)Text Comparison::.
 
  -- Function: string-split string &optional separators omit-nulls trim
      ‘string-split’ is an alias for the function ‘split-string’.  The
      name follows the convention of other string functions.
 
      *Note (elisp)Creating Strings::.
 
  -- Function: buffer-match-p condition buffer-or-name &optional arg
      This function checks if a buffer designated by ‘buffer-or-name’
      satisfies a ‘condition’.  Optional third argument ARG is passed to
      the predicate function in CONDITION.  A condition can be one of the
      following:
         • A string, interpreted as a regular expression.  The buffer
           satisfies the condition if the regular expression matches the
           buffer name.
         • A predicate function, which should return non-‘nil’ if the
           buffer matches.  If the function expects one argument, it is
           called with BUFFER-OR-NAME as the argument; if it expects 2
           arguments, the first argument is BUFFER-OR-NAME and the second
           is ARG (or ‘nil’ if ARG is omitted).
         • A cons-cell ‘(OPER . EXPR)’ where OPER is one of
           ‘not’
                Satisfied if EXPR doesn’t satisfy ‘buffer-match-p’ with
                the same buffer and ‘arg’.
           ‘or’
                Satisfied if EXPR is a list and _any_ condition in EXPR
                satisfies ‘buffer-match-p’, with the same buffer and
                ‘arg’.
           ‘and’
                Satisfied if EXPR is a list and _all_ conditions in EXPR
                satisfy ‘buffer-match-p’, with the same buffer and ‘arg’.
           ‘derived-mode’
                Satisfied if the buffer’s major mode derives from EXPR.
           ‘major-mode’
                Satisfied if the buffer’s major mode is equal to EXPR.
                Prefer using ‘derived-mode’ instead when both can work.
         • t Satisfied by any buffer.  A convenient alternative to ‘""’
           (empty string), ‘(and)’ (empty conjunction) or ‘always’.
 
      *Note (elisp)Buffer List::.
 
  -- Function: match-buffers condition &optional buffers arg
      This function returns a list of all buffers that satisfy a
      ‘condition’, as defined for ‘buffer-match-p’.  By default all
      buffers are considered, but this can be restricted via the second
      optional ‘buffer-list’ argument.  Optional third argument ARG will
      be used by CONDITION in the same way as ‘buffer-match-p’ does.
 
      *Note (elisp)Buffer List::.
 
  -- Function: string-glyph-split string
      When character compositions are in effect, sequence of characters
      can be composed for display to form _grapheme clusters_, for
      example to display accented characters, or ligatures, or Emoji, or
      when complex text shaping requires that for some scripts.  When
      that happens, characters no longer map in a simple way to display
      columns, and display layout decisions with such strings, such as
      truncating too wide strings, can be a complex job.  This function
      helps in performing such jobs: it splits up its argument STRING
      into a list of substrings, where each substring produces a single
      grapheme cluster that should be displayed as a unit.  Lisp programs
      can then use this list to construct visually-valid substrings of
      STRING which will look correctly on display, or compute the width
      of any substring of STRING by adding the width of its constituents
      in the returned list, etc.
 
      For instance, if you want to display a string without the first
      glyph, you can say:
 
           (apply #'insert (cdr (string-glyph-split string))))
 
      *Note (elisp)Size of Displayed Text::.
 
  -- Macro: with-buffer-unmodified-if-unchanged &rest body...
      Evaluate BODY like ‘progn’, but change buffer-modified status only
      if buffer text changes.  If the buffer was unmodified before
      execution of BODY, and buffer text after execution of BODY is
      identical to what it was before, ensure that buffer is still marked
      unmodified afterwards.
 
      Note that only changes in the raw byte sequence of the buffer text,
      as stored in the internal representation, are monitored for the
      purpose of detecting the lack of changes in buffer text.  Any other
      changes that are normally perceived as "buffer modifications", such
      as changes in text properties, ‘buffer-file-coding-system’, buffer
      multibyteness, etc.  – will not be noticed, and the buffer will
      still be marked unmodified, effectively ignoring those changes.
 
  -- Function: file-attribute-file-identifier
      Return the fields ‘(inodenum device)’ as a list from attributes
      generated by ‘file-attributes’.
 
      *Note (elisp)File Attributes::.
 
  -- Function: file-name-split filename
      This function splits a file name into its components, and can be
      thought of as the inverse of ‘string-join’ with the appropriate
      directory separator.  For example,
 
           (file-name-split "/tmp/foo.txt")
               ⇒ ("" "tmp" "foo.txt")
           (string-join (file-name-split "/tmp/foo.txt") "/")
               ⇒ "/tmp/foo.txt"
 
  -- Function: file-name-parent-directory filename
      This function returns the directory name of the parent directory of
      FILENAME.  If FILENAME is at the root directory of the filesystem,
      it returns ‘nil’.  A relative FILENAME is assumed to be relative to
      ‘default-directory’, and the return value will also be relative in
      that case.  If the return value is non-‘nil’, it ends in a slash.
 
      *Note (elisp)Directory Names::.
 
  -- Function: file-has-changed-p file &optional tag
      This function returns non-‘nil’ if the time stamp of FILENAME has
      changed since the last call.  When called for the first time for
      some FILENAME, it records the last modification time and size of
      the file, and returns non-‘nil’ when FILENAME exists.  Thereafter,
      when called for the same FILENAME, it compares the current time
      stamp and size with the recorded ones, and returns non-‘nil’ only
      if either the time stamp or the size (or both) are different.  This
      is useful when a Lisp program wants to re-read a file whenever it
      changes.  With an optional argument TAG, which must be a symbol,
      the size and modification time comparisons are limited to calls
      with the same tag.
 
      *Note (elisp)File Attributes::.
 
  -- Function: directory-abbrev-make-regexp directory
      Create a regexp to match DIRECTORY for ‘directory-abbrev-alist’.
 
  -- Function: directory-abbrev-apply filename
      Apply the abbreviations in ‘directory-abbrev-alist’ to FILENAME.
      Note that when calling this, you should set ‘case-fold-search’ as
      appropriate for the filesystem used for FILENAME.
 
  -- Function: key-valid-p keys
      Say whether KEYS is a valid key.  A key is a string consisting of
      one or more key strokes.  The key strokes are separated by single
      space characters.
 
      Each key stroke is either a single character, or the name of an
      event, surrounded by angle brackets.  In addition, any key stroke
      may be preceded by one or more modifier keys.  Finally, a limited
      number of characters have a special shorthand syntax.
 
      Here’s some example key sequences.
 
      ‘f’
           The key ‘f’.
      ‘S o m’
           A three key sequence of the keys ‘S’, ‘o’ and ‘m’.
      ‘C-c o’
           A two key sequence of the keys ‘c’ with the control modifier
           and then the key ‘o’.
      ‘H-<left>’
           The key named "left" with the hyper modifier.
      ‘M-RET’
           The "return" key with a meta modifier.
      ‘C-M-<space>’
           The "space" key with both the control and meta modifiers.
 
      These are the characters that have shorthand syntax: ‘NUL’, ‘RET’,
      ‘TAB’, ‘LFD’, ‘ESC’, ‘SPC’, ‘DEL’.
 
      Modifiers have to be specified in this order
      Alt (A)-Control (C)-Hyper (H)-Meta (M)-Shift (s)-Super (s)
 
  -- Function: key-parse keys
      Convert KEYS to the internal Emacs key representation.  See
      ‘key-valid-p’ for a description of valid key sequences.  Examples
      include ‘f’, ‘C-c C-c’, ‘H-<left>’, ‘M-RET’ or ‘C-M-<return>’.
 
  -- Function: keymap-set keymap key definition
      This function sets the binding for KEY in KEYMAP.  (If KEY is more
      than one event long, the change is actually made in another keymap
      reached from KEYMAP.)  The argument BINDING can be any Lisp object,
      but only certain types are meaningful.  (For a list of meaningful
      types, see *note (elisp)Key Lookup::.)  The value returned by
      ‘keymap-set’ is BINDING.
 
      If KEY is ‘<t>’, this sets the default binding in KEYMAP.  When an
      event has no binding of its own, the Emacs command loop uses the
      keymap’s default binding, if there is one.
 
      Every prefix of KEY must be a prefix key (i.e., bound to a keymap)
      or undefined; otherwise an error is signaled.  If some prefix of
      KEY is undefined, then ‘keymap-set’ defines it as a prefix key so
      that the rest of KEY can be defined as specified.
 
      If there was previously no binding for KEY in KEYMAP, the new
      binding is added at the beginning of KEYMAP.  The order of bindings
      in a keymap makes no difference for keyboard input, but it does
      matter for menu keymaps (*note (elisp)Menu Keymaps::).
 
      *Note (elisp)Changing Key Bindings::.
 
  -- Function: keymap-global-set key command
      This function sets the binding of KEY in the current global map to
      BINDING.
 
           (keymap-global-set KEY BINDING)
           ≡
           (keymap-set (current-global-map) KEY BINDING)
 
      *Note (elisp)Key Binding Commands::.
 
  -- Function: keymap-local-set key command
      This function sets the binding of KEY in the current local keymap
      to BINDING.
 
           (keymap-local-set KEY BINDING)
           ≡
           (keymap-set (current-local-map) KEY BINDING)
 
      *Note (elisp)Key Binding Commands::.
 
  -- Function: keymap-global-unset key &optional remove
      This function removes the binding of KEY from the current global
      map.
 
      One use of this function is in preparation for defining a longer
      key that uses KEY as a prefix—which would not be allowed if KEY has
      a non-prefix binding.  For example:
 
           (keymap-global-unset "C-l")
               ⇒ nil
           (keymap-global-set "C-l C-l" 'redraw-display)
               ⇒ nil
 
      *Note (elisp)Key Binding Commands::.
 
  -- Function: keymap-local-unset key &optional remove
      This function removes the binding of KEY from the current local
      map.
 
      *Note (elisp)Key Binding Commands::.
 
  -- Function: keymap-substitute keymap olddef newdef &optional oldmap
           prefix
      Replace OLDDEF with NEWDEF for any keys in KEYMAP now defined as
      OLDDEF.  In other words, OLDDEF is replaced with NEWDEF wherever it
      appears.  Alternatively, if optional fourth argument OLDMAP is
      specified, we redefine in KEYMAP as NEWDEF those keys that are
      defined as OLDDEF in OLDMAP.
 
  -- Function: keymap-lookup keymap key &optional accept-default no-remap
           position
      This function returns the definition of KEY in KEYMAP.  All the
      other functions described in this chapter that look up keys use
      ‘keymap-lookup’.  Here are examples:
 
           (keymap-lookup (current-global-map) "C-x C-f")
               ⇒ find-file
           (keymap-lookup (current-global-map) "C-x C-f 1 2 3 4 5")
               ⇒ 2
 
      *Note (elisp)Functions for Key Lookup::.
 
  -- Function: keymap-local-lookup keys &optional accept-default
      Like ‘keymap-lookup’, but restricting the search for commands bound
      to KEYS to the current local keymap.
 
  -- Function: keymap-global-lookup keys &optional accept-default
      Like ‘keymap-lookup’, but restricting the search for commands bound
      to KEYS to the current global keymap.
 
  -- Function: define-keymap &rest definitions
      You can create a keymap with the functions described above, and
      then use ‘keymap-set’ (*note (elisp)Changing Key Bindings::) to
      specify key bindings in that map.  When writing modes, however, you
      frequently have to bind a large number of keys at once, and using
      ‘keymap-set’ on them all can be tedious and error-prone.  Instead
      you can use ‘define-keymap’, which creates a keymap and binds a
      number of keys.  Here’s a very basic example:
 
           (define-keymap
             "n" #'forward-line
             "f" #'previous-line
             "C-c C-c" #'quit-window)
 
      This function creates a new sparse keymap, defines the keystrokes
      in PAIRS, and returns the new keymap.
 
      PAIRS is a list of alternating key bindings and key definitions, as
      accepted by ‘keymap-set’.  In addition, the key can be the special
      symbol ‘:menu’, in which case the definition should be a menu
      definition as accepted by ‘easy-menu-define’ (*note (elisp)Easy
      Menu::).  Here’s a brief example of this usage:
 
           (define-keymap :full t
             "g" #'eww-reload
             :menu '("Eww"
                     ["Exit" quit-window t]
                     ["Reload" eww-reload t]))
 
      A number of keywords can be used before the key/definition pairs to
      change features of the new keymap.  If any of the feature keywords
      is missing from the ‘define-keymap’ call, the default value for
      that feature is ‘nil’.  Here’s a list of the available feature
      keywords:
 
      ‘:full’
           If non-‘nil’, create a char-table keymap (as from
           ‘make-keymap’) instead of a sparse keymap (as from
           ‘make-sparse-keymap’ (*note (elisp)Creating Keymaps::).  A
           sparse keymap is the default.
 
      ‘:parent’
           If non-‘nil’, the value should be a keymap to use as the
           parent (*note (elisp)Inheritance and Keymaps::).
 
      ‘:keymap’
           If non-‘nil’, the value should be a keymap.  Instead of
           creating a new keymap, the specified keymap is modified
           instead.
 
      ‘:suppress’
           If non-‘nil’, the keymap will be suppressed with
           ‘suppress-keymap’ (*note (elisp)Changing Key Bindings::).  By
           default, digits and the minus sign are exempt from
           suppressing, but if the value is ‘nodigits’, this suppresses
           digits and minus-sign like it does with other characters.
 
      ‘:name’
           If non-‘nil’, the value should be a string to use as the menu
           for the keymap if you use it as a menu with ‘x-popup-menu’
           (*note (elisp)Pop-Up Menus::).
 
      ‘:prefix’
           If non-‘nil’, the value should be a symbol to be used as a
           prefix command (*note (elisp)Prefix Keys::).  If this is the
           case, this symbol is returned by ‘define-keymap’ instead of
           the map itself.
 
  -- Function: defvar-keymap (variable-name &rest defs)
      By far, the most common thing to do with a keymap is to bind it to
      a variable.  This is what virtually all modes do—a mode called
      ‘foo’ almost always has a variable called ‘foo-mode-map’.
 
      This macro defines NAME as a variable, passes OPTIONS and PAIRS to
      ‘define-keymap’, and uses the result as the default value for the
      variable.
 
      OPTIONS is like the keywords in ‘define-keymap’, but there’s an
      additional ‘:doc’ keyword that provides the doc string for the
      defined variable.
 
      Here’s an example:
 
           (defvar-keymap eww-textarea-map
             :parent text-mode-map
             "RET" #'forward-line
             "TAB" #'shr-next-link)
 
  -- Macro: while-let spec then-forms...
      Like ‘when-let’, but repeat until a binding in SPEC is ‘nil’.  The
      return value is always ‘nil’.
 
      This is comparable to ‘and-let*’.
 
  -- Function: window-configuration-equal-p config1 config2
      This function says whether two window configurations have the same
      window layout, but ignores the values of point and the saved
      scrolling positions—it can return ‘t’ even if those aspects differ.
 
  -- Macro: ert-with-temp-file name &rest body
      Bind NAME to the name of a new temporary file and evaluate BODY.
      Delete the temporary file after BODY exits normally or non-locally.
      NAME will be bound to the file name of the temporary file.  See the
      docstring for supported keyword arguments.
 
  -- Macro: ert-with-temp-directory name &rest body
      Bind NAME to the name of a new temporary directory and evaluate
      BODY.  Delete the temporary directory after BODY exits normally or
      non-locally.
 
      NAME is bound to the directory name, not the directory file name.
      (In other words, it will end with the directory delimiter; on
      Unix-like systems, it will end with "/".)
 
      The same keyword arguments are supported as in ‘ert-with-temp-file’
      (which see), except for ‘:text’.
 
  -- Function: cl-constantly value
      Return a function that takes any number of arguments, but returns
      VALUE.
 
  -- Macro: cl-with-gensyms names... body
      This macro expands to code that executes BODY with each of the
      variables in NAMES bound to a fresh uninterned symbol, or “gensym”,
      in Common Lisp parlance.  For macros requiring more than one
      gensym, use of ‘cl-with-gensyms’ shortens the code and renders
      one’s intentions clearer.  Compare:
 
           (defmacro my-macro (foo)
             (let ((bar (gensym "bar"))
                   (baz (gensym "baz"))
                   (quux (gensym "quux")))
               `(let ((,bar (+ ...)))
                  ...)))
 
           (defmacro my-macro (foo)
             (cl-with-gensyms (bar baz quux)
               `(let ((,bar (+ ...)))
                  ...)))
 
  -- Macro: cl-once-only ((variable form)...) body
      This macro is primarily to help the macro programmer ensure that
      forms supplied by the user of the macro are evaluated just once by
      its expansion even though the result of evaluating the form is to
      occur more than once.  Less often, this macro is used to ensure
      that forms supplied by the macro programmer are evaluated just
      once.
 
      Each VARIABLE may be used to refer to the result of evaluating FORM
      in BODY.  ‘cl-once-only’ binds each VARIABLE to a fresh uninterned
      symbol during the evaluation of BODY.  Then, ‘cl-once-only’ wraps
      the final expansion in code to evaluate each FORM and bind the
      result to the corresponding uninterned symbol.  Thus, when the
      macro writer substitutes the value for VARIABLE into the expansion
      they are effectively referring to the result of evaluating FORM,
      rather than FORM itself.  Another way to put this is that each
      VARIABLE is bound to an expression for the (singular) result of
      evaluating FORM.
 
      The most common case is where VARIABLE is one of the arguments to
      the macro being written, so ‘(variable variable)’ may be
      abbreviated to just ‘variable’.
 
      For example, consider this macro:
 
           (defmacro my-list (x y &rest forms)
             (let ((x-result (gensym))
                   (y-result (gensym)))
               `(let ((,x-result ,x)
                      (,y-result ,y))
                  (list ,x-result ,y-result ,x-result ,y-result
                        (progn ,@forms))))
 
      In a call like ‘(my-list (pop foo) ...)’ the intermediate binding
      to ‘x-result’ ensures that the ‘pop’ is not done twice.  But as a
      result the code is rather complex: the reader must keep track of
      how ‘x-result’ really just means the first parameter of the call to
      the macro, and the required use of multiple gensyms to avoid
      variable capture by ‘(progn ,@forms)’ obscures things further.
      ‘cl-once-only’ takes care of these details:
 
           (defmacro my-list (x y &rest forms)
             (cl-once-only (x y)
               `(list ,x ,y ,x ,y
                      (progn ,@forms))))
 
 2.5.2 Extended Definitions
 --------------------------
 
 These functions must be called explicitly via ‘compat-call’, since their
 calling convention or behavior was extended in Emacs 29.1:
 
  -- Function: compat-call set-transient-map keymap &optional keep-pred
           on-exit message timeout
      This function adds KEYMAP as a “transient” keymap, which takes
      precedence over other keymaps for one (or more) subsequent keys.
 
      Normally, KEYMAP is used just once, to look up the very next key.
      If the optional argument KEEP-PRED is ‘t’, the map stays active as
      long as the user types keys defined in KEYMAP; when the user types
      a key that is not in KEYMAP, the transient keymap is deactivated
      and normal key lookup continues for that key.
 
      The KEEP-PRED argument can also be a function.  In that case, the
      function is called with no arguments, prior to running each
      command, while KEYMAP is active; it should return non-‘nil’ if
      KEYMAP should stay active.
 
      The optional argument ON-EXIT, if non-‘nil’, specifies a function
      that is called, with no arguments, after KEYMAP is deactivated.
 
      The optional argument MESSAGE specifies the message to display
      after activating the transient map.  If MESSAGE is a string, it is
      the format string for the message, and any ‘%k’ specifier in that
      string is replaced with the list of keys from the transient map.
      Any other non-‘nil’ value of MESSAGE stands for the default message
      format ‘Repeat with %k’.
 
      If the optional argument TIMEOUT is non-‘nil’, it should be a
      number that specifies how many seconds of idle time to wait before
      deactivating KEYMAP.  The value of the variable
      ‘set-transient-map-timeout’, if non-‘nil’, overrides the value of
      this argument.
 
      This function works by adding and removing KEYMAP from the variable
      ‘overriding-terminal-local-map’, which takes precedence over all
      other active keymaps (*note (Searching Keymaps)elisp::).
 
  -- Function: compat-call string-lines string &optional omit-nulls
           keep-newlines
      Split STRING into a list of strings on newline boundaries.  If the
      optional argument OMIT-NULLS is non-‘nil’, remove empty lines from
      the results.  If the optional argument KEEP-NEWLINES is non-‘nil’,
      don’t remove the trailing newlines from the result strings.
 
      *Note (elisp)Creating Strings::.
 
  -- Function: compat-call define-key
      This function is like ‘keymap-set’ (*note (elisp)Changing Key
      Bindings::, but understands only the legacy key syntaxes.
 
      In addition, this function also has a REMOVE argument.  If it is
      non-‘nil’, the definition will be removed.  This is almost the same
      as setting the definition to ‘nil’, but makes a difference if the
      KEYMAP has a parent, and KEY is shadowing the same binding in the
      parent.  With REMOVE, subsequent lookups will return the binding in
      the parent, whereas with a ‘nil’ definition the lookups will return
      ‘nil’.
 
      *Note (elisp)Low-Level Key Binding::.
 
      This compatibility version handles the optional argument REMOVE.
 
  -- Function: compat-call plist-get plist prop &optional predicate
      This returns the value of the PROPERTY property stored in the
      property list PLIST.  Comparisons are done with PREDICATE, and
      defaults to ‘eq’.  It accepts a malformed PLIST argument.  If
      PROPERTY is not found in the PLIST, it returns ‘nil’.
 
      *Note (elisp)Plist Access::.
 
      This compatibility version handles the optional argument PREDICATE.
      This is a generalized variable (*note (elisp)Generalized
      Variables::) that can be used to change a value with ‘setf’.
 
  -- Function: compat-call plist-put plist prop val &optional predicate
      This stores VALUE as the value of the PROPERTY property in the
      property list PLIST.  Comparisons are done with PREDICATE, and
      defaults to ‘eq’.  It may modify PLIST destructively, or it may
      construct a new list structure without altering the old.  The
      function returns the modified property list, so you can store that
      back in the place where you got PLIST.
 
      *Note (elisp)Plist Access::.
 
      This compatibility version handles the optional argument PREDICATE.
 
  -- Function: compat-call plist-member plist prop &optional predicate
      This returns non-‘nil’ if PLIST contains the given PROPERTY.
      Comparisons are done with PREDICATE, and defaults to ‘eq’.  Unlike
      ‘plist-get’, this allows you to distinguish between a missing
      property and a property with the value ‘nil’.  The value is
      actually the tail of PLIST whose ‘car’ is PROPERTY.
 
      *Note (elisp)Plist Access::.
 
      This compatibility version handles the optional argument PREDICATE.
 
 2.5.3 Missing Definitions
 -------------------------
 
 Compat does not provide support for the following Lisp features
 implemented in 29.1:
 
    • The function ‘imagep’.
    • The function ‘image-at-point-p’.
    • The function ‘function-documentation’.
    • The macro ‘with-undo-amalgamate’.
    • The function ‘string-glyph-split’.
    • The function ‘string-limit’.
    • The function ‘string-pixel-width’ and ‘buffer-text-pixel-size’.
    • The function ‘minibuffer-lazy-highlight-setup’.
    • The function ‘pp-emacs-lisp-code’.
    • The function ‘bidi-string-strip-control-characters’.
    • The native function ‘current-cpu-time’.
    • The functions ‘xdg-state-home’, ‘xdg-current-desktop’ and
      ‘xdg-session-type’.
    • The macro ‘setopt’.
    • The ‘oclosure’ library.
    • The ‘textsec’ library.
    • The ‘range’ library.
    • The ‘string-edit’ library.
    • The ‘vtable’ library.
    • The ‘pixel-fill’ library.
    • Support for symbols with position information.
 
 
 File: docXccUUB.info,  Node: Development,  Next: Function Index,  Prev: Support,  Up: Top
 
 3 Development
 *************
 
 Compat is developed on GitHub.
 
    Bug reports, patches and comments are best sent to the issue tracker
 (https://github.com/emacs-compat/compat/issues).  These may include
 issues in the compatibility code, missing definitions or performance
 issues.  We also provide a development mailing list
 (https://lists.sr.ht/~pkal/compat-devel) (~pkal/compat-devel@lists.sr.ht
 <~pkal/compat-devel@lists.sr.ht>).
 
    Please note that as a GNU ELPA package, Compat requires contributors
 to have signed the FSF copyright assignment
 (https://www.gnu.org/software/emacs/manual/html_node/emacs/Copyright-Assignment.html),
 before any non-trivial contribution (roughly 15 lines of code) can be
 applied.
 
    It is important that you provide tests when you contribute new
 functionality.  Compat has 100% test coverage by the test suite.  We use
 continuous integration to check if patches preserve existing
 functionality.
 
    Development for the currently stable Emacs version happens in the
 main branch of the Compat Git repository.  ELPA-devel nightly builds are
 created from this branch.  New features, which are not yet ready to be
 merged directly into the main branch, are developed in feature branches.
 Furthermore the Git repository has a branch emacs-<version> where the
 development for the upcoming Emacs release takes place.  This branch is
 separate from the main branch since the new functionality should not be
 made available (neither via ELPA nor ELPA-devel) before the new Emacs
 version has been reasonably stabilized, e.g., around the time when the
 Emacs version branch is created in the Emacs repository on Savannah.
 
 
 File: docXccUUB.info,  Node: Function Index,  Next: Variable Index,  Prev: Development,  Up: Top
 
 Appendix A Function Index
 *************************
 
 
 * Menu:
 
 * add-display-text-property:             Emacs 29.1.          (line 190)
 * alist-get:                             Emacs 25.1.          (line  82)
 * always:                                Emacs 28.1.          (line  83)
 * and-let*:                              Emacs 26.1.          (line 158)
 * assoc-delete-all:                      Emacs 26.1.          (line  13)
 * bignump:                               Emacs 27.1.          (line  55)
 * bool-vector:                           Emacs 25.1.          (line 177)
 * bounds-of-thing-at-mouse:              Emacs 28.1.          (line 292)
 * buffer-hash:                           Emacs 26.1.          (line  80)
 * buffer-local-boundp:                   Emacs 28.1.          (line 125)
 * buffer-local-restore-state:            Emacs 29.1.          (line  50)
 * buffer-local-set-state:                Emacs 29.1.          (line  50)
 * buffer-match-p:                        Emacs 29.1.          (line 258)
 * buttonize:                             Emacs 29.1.          (line 156)
 * buttonize-region:                      Emacs 29.1.          (line 165)
 * char-uppercase-p:                      Emacs 29.1.          (line 127)
 * cl-constantly:                         Emacs 29.1.          (line 635)
 * cl-once-only:                          Emacs 29.1.          (line 658)
 * cl-with-gensyms:                       Emacs 29.1.          (line 639)
 * color-dark-p:                          Emacs 28.1.          (line 322)
 * color-values-from-color-spec:          Emacs 28.1.          (line 328)
 * compat-call:                           Usage.               (line  50)
 * compat-call alist-get:                 Emacs 26.1.          (line 344)
 * compat-call assoc:                     Emacs 26.1.          (line 316)
 * compat-call assoc-delete-all:          Emacs 27.1.          (line 417)
 * compat-call count-windows:             Emacs 28.1.          (line 412)
 * compat-call define-key:                Emacs 29.1.          (line 755)
 * compat-call executable-find:           Emacs 27.1.          (line 429)
 * compat-call file-size-human-readable:  Emacs 27.1.          (line 397)
 * compat-call line-number-at-pos:        Emacs 26.1.          (line 330)
 * compat-call lookup-key:                Emacs 27.1.          (line 356)
 * compat-call make-temp-file:            Emacs 26.1.          (line 278)
 * compat-call plist-get:                 Emacs 29.1.          (line 771)
 * compat-call plist-member:              Emacs 29.1.          (line 795)
 * compat-call plist-put:                 Emacs 29.1.          (line 783)
 * compat-call recenter:                  Emacs 27.1.          (line 346)
 * compat-call regexp-opt:                Emacs 27.1.          (line 385)
 * compat-call set-transient-map:         Emacs 29.1.          (line 710)
 * compat-call setq-local:                Emacs 27.1.          (line 370)
 * compat-call sort:                      Emacs 25.1.          (line 189)
 * compat-call string-lines:              Emacs 29.1.          (line 746)
 * compat-call string-trim:               Emacs 26.1.          (line 375)
 * compat-call string-trim-left:          Emacs 26.1.          (line 359)
 * compat-call string-trim-right:         Emacs 26.1.          (line 367)
 * compat-call string-width:              Emacs 28.1.          (line 395)
 * compat-function:                       Usage.               (line  58)
 * compiled-function-p:                   Emacs 29.1.          (line 226)
 * count-sentences:                       Emacs 29.1.          (line  25)
 * cXXXr:                                 Emacs 26.1.          (line  66)
 * cXXXXr:                                Emacs 26.1.          (line  67)
 * date-days-in-month:                    Emacs 27.1.          (line 213)
 * date-ordinal-to-time:                  Emacs 27.1.          (line 220)
 * decoded-time-day:                      Emacs 27.1.          (line 175)
 * decoded-time-dst:                      Emacs 27.1.          (line 195)
 * decoded-time-hour:                     Emacs 27.1.          (line 170)
 * decoded-time-minute:                   Emacs 27.1.          (line 165)
 * decoded-time-month:                    Emacs 27.1.          (line 180)
 * decoded-time-period:                   Emacs 28.1.          (line 359)
 * decoded-time-second:                   Emacs 27.1.          (line 160)
 * decoded-time-weekday:                  Emacs 27.1.          (line 190)
 * decoded-time-year:                     Emacs 27.1.          (line 185)
 * decoded-time-zone:                     Emacs 27.1.          (line 200)
 * define-keymap:                         Emacs 29.1.          (line 518)
 * defvar-keymap:                         Emacs 29.1.          (line 586)
 * delete-line:                           Emacs 29.1.          (line  59)
 * directory-abbrev-apply:                Emacs 29.1.          (line 382)
 * directory-abbrev-make-regexp:          Emacs 29.1.          (line 379)
 * directory-empty-p:                     Emacs 28.1.          (line 243)
 * directory-name-p:                      Emacs 25.1.          (line  56)
 * dlet:                                  Emacs 28.1.          (line 143)
 * dolist-with-progress-reporter:         Emacs 27.1.          (line 119)
 * ensure-list:                           Emacs 28.1.          (line 158)
 * ert-with-temp-directory:               Emacs 29.1.          (line 623)
 * ert-with-temp-file:                    Emacs 29.1.          (line 617)
 * file-attribute-access-time:            Emacs 26.1.          (line 223)
 * file-attribute-collect:                Emacs 26.1.          (line 260)
 * file-attribute-device-number:          Emacs 26.1.          (line 255)
 * file-attribute-file-identifier:        Emacs 29.1.          (line 339)
 * file-attribute-group-id:               Emacs 26.1.          (line 218)
 * file-attribute-inode-number:           Emacs 26.1.          (line 250)
 * file-attribute-link-number:            Emacs 26.1.          (line 208)
 * file-attribute-modes:                  Emacs 26.1.          (line 245)
 * file-attribute-modification-time:      Emacs 26.1.          (line 228)
 * file-attribute-size:                   Emacs 26.1.          (line 240)
 * file-attribute-status-change-time:     Emacs 26.1.          (line 234)
 * file-attribute-type:                   Emacs 26.1.          (line 203)
 * file-attribute-user-id:                Emacs 26.1.          (line 213)
 * file-backup-file-names:                Emacs 28.1.          (line 347)
 * file-has-changed-p:                    Emacs 29.1.          (line 364)
 * file-local-name:                       Emacs 26.1.          (line 167)
 * file-modes-number-to-symbolic:         Emacs 28.1.          (line 341)
 * file-name-concat:                      Emacs 28.1.          (line  53)
 * file-name-parent-directory:            Emacs 29.1.          (line 355)
 * file-name-quote:                       Emacs 26.1.          (line 102)
 * file-name-quoted-p:                    Emacs 26.1.          (line  95)
 * file-name-split:                       Emacs 29.1.          (line 345)
 * file-name-unquote:                     Emacs 26.1.          (line  90)
 * file-name-with-extension:              Emacs 28.1.          (line 225)
 * file-size-human-readable-iec:          Emacs 27.1.          (line 251)
 * fixnump:                               Emacs 27.1.          (line  60)
 * flatten-tree:                          Emacs 27.1.          (line 132)
 * format-message:                        Emacs 25.1.          (line  44)
 * format-prompt:                         Emacs 28.1.          (line 254)
 * funcall-with-delayed-message:          Emacs 29.1.          (line 148)
 * function-alias-p:                      Emacs 29.1.          (line 233)
 * garbage-collect-maybe:                 Emacs 28.1.          (line  68)
 * gensym:                                Emacs 26.1.          (line  70)
 * get-display-property:                  Emacs 29.1.          (line 173)
 * get-scratch-buffer-create:             Emacs 29.1.          (line  38)
 * hash-table-empty:                      Emacs 25.1.          (line 119)
 * if-let:                                Emacs 25.1.          (line  96)
 * if-let*:                               Emacs 26.1.          (line 149)
 * ignore-errors:                         Emacs 27.1.          (line 106)
 * image-property:                        Emacs 26.1.          (line 198)
 * insert-into-buffer:                    Emacs 28.1.          (line  92)
 * key-parse:                             Emacs 29.1.          (line 419)
 * key-valid-p:                           Emacs 29.1.          (line 387)
 * keymap-global-lookup:                  Emacs 29.1.          (line 514)
 * keymap-global-set:                     Emacs 29.1.          (line 448)
 * keymap-global-unset:                   Emacs 29.1.          (line 468)
 * keymap-local-lookup:                   Emacs 29.1.          (line 510)
 * keymap-local-set:                      Emacs 29.1.          (line 458)
 * keymap-local-unset:                    Emacs 29.1.          (line 483)
 * keymap-lookup:                         Emacs 29.1.          (line 497)
 * keymap-set:                            Emacs 29.1.          (line 424)
 * keymap-substitute:                     Emacs 29.1.          (line 489)
 * length<:                               Emacs 28.1.          (line  45)
 * length=:                               Emacs 28.1.          (line  42)
 * length>:                               Emacs 28.1.          (line  50)
 * list-of-strings-p:                     Emacs 29.1.          (line  62)
 * macroexp-file-name:                    Emacs 28.1.          (line 301)
 * macroexp-parse:                        Emacs 25.1.          (line 174)
 * macroexp-quote:                        Emacs 25.1.          (line 171)
 * macroexp-warn-and-return:              Emacs 28.1.          (line 305)
 * macroexpand-1:                         Emacs 25.1.          (line 164)
 * major-mode-restore:                    Emacs 27.1.          (line  22)
 * major-mode-suspend:                    Emacs 27.1.          (line  13)
 * make-empty-file:                       Emacs 27.1.          (line 254)
 * make-lock-file-name:                   Emacs 28.1.          (line 355)
 * make-nearby-temp-file:                 Emacs 26.1.          (line 120)
 * make-separator-line:                   Emacs 28.1.          (line  88)
 * mapcan:                                Emacs 26.1.          (line  53)
 * mark-thing-at-mouse:                   Emacs 28.1.          (line 298)
 * match-buffers:                         Emacs 29.1.          (line 292)
 * minibuffer-history-value:              Emacs 27.1.          (line  32)
 * named-let:                             Emacs 28.1.          (line 207)
 * native-comp-available-p:               Emacs 28.1.          (line 376)
 * ntake:                                 Emacs 29.1.          (line 213)
 * package-get-version:                   Emacs 27.1.          (line 205)
 * plistp:                                Emacs 29.1.          (line  65)
 * pos-bol:                               Emacs 29.1.          (line 119)
 * pos-eol:                               Emacs 29.1.          (line 123)
 * process-lines-handling-status:         Emacs 28.1.          (line  20)
 * process-lines-ignore-status:           Emacs 28.1.          (line  16)
 * proper-list-p:                         Emacs 27.1.          (line  76)
 * provided-mode-derived-p:               Emacs 27.1.          (line 247)
 * read-answer:                           Emacs 26.1.          (line  17)
 * read-char-from-minibuffer:             Emacs 27.1.          (line  44)
 * read-multiple-choice:                  Emacs 26.1.          (line 185)
 * readablep:                             Emacs 29.1.          (line  28)
 * region-bounds:                         Emacs 25.1.          (line  28)
 * region-noncontiguous-p:                Emacs 25.1.          (line  34)
 * replace-regexp-in-string:              Emacs 28.1.          (line 117)
 * replace-string-in-region:              Emacs 28.1.          (line 102)
 * ring-resize:                           Emacs 27.1.          (line  28)
 * save-mark-and-excursion:               Emacs 25.1.          (line  39)
 * string-chop-newline:                   Emacs 28.1.          (line 202)
 * string-clean-whitespace:               Emacs 28.1.          (line 171)
 * string-distance:                       Emacs 27.1.          (line  86)
 * string-equal-ignore-case:              Emacs 29.1.          (line 246)
 * string-fill:                           Emacs 28.1.          (line 178)
 * string-glyph-split:                    Emacs 29.1.          (line 301)
 * string-greaterp:                       Emacs 25.1.          (line  64)
 * string-lines:                          Emacs 28.1.          (line 186)
 * string-pad:                            Emacs 28.1.          (line 193)
 * string-replace:                        Emacs 28.1.          (line  77)
 * string-search:                         Emacs 28.1.          (line  34)
 * string-split:                          Emacs 29.1.          (line 252)
 * subr-native-elisp-p:                   Emacs 28.1.          (line 371)
 * subr-primitive-p:                      Emacs 28.1.          (line 364)
 * substitute-quotes:                     Emacs 29.1.          (line  34)
 * take:                                  Emacs 29.1.          (line 199)
 * temporary-file-directory:              Emacs 26.1.          (line 137)
 * text-property-search-backward:         Emacs 27.1.          (line 332)
 * text-property-search-forward:          Emacs 27.1.          (line 260)
 * text-quoting-style:                    Emacs 28.1.          (line  28)
 * thing-at-mouse:                        Emacs 28.1.          (line 285)
 * thread-first:                          Emacs 25.1.          (line 122)
 * thread-last:                           Emacs 25.1.          (line 143)
 * time-equal-p:                          Emacs 27.1.          (line 208)
 * use-region-beginning:                  Emacs 29.1.          (line  47)
 * use-region-end:                        Emacs 29.1.          (line  44)
 * use-region-noncontiguous-p:            Emacs 29.1.          (line  41)
 * when-let:                              Emacs 25.1.          (line 114)
 * when-let*:                             Emacs 26.1.          (line 153)
 * while-let:                             Emacs 29.1.          (line 606)
 * window-configuration-equal-p:          Emacs 29.1.          (line 612)
 * with-buffer-unmodified-if-unchanged:   Emacs 29.1.          (line 324)
 * with-delayed-message:                  Emacs 29.1.          (line 131)
 * with-environment-variables:            Emacs 28.1.          (line 309)
 * with-existing-directory:               Emacs 28.1.          (line 132)
 * with-file-modes:                       Emacs 25.1.          (line  71)
 * with-memoization:                      Emacs 29.1.          (line  68)
 * with-minibuffer-selected-window:       Emacs 27.1.          (line  38)
 * with-restriction:                      Emacs 29.1.          (line  73)
 * with-suppressed-warnings:              Emacs 27.1.          (line  65)
 * with-window-non-dedicated:             Emacs 28.1.          (line 384)
 * without-restriction:                   Emacs 29.1.          (line 107)
 * xor:                                   Emacs 27.1.          (line 142)
 
 
 File: docXccUUB.info,  Node: Variable Index,  Prev: Function Index,  Up: Top
 
 Appendix B Variable Index
 *************************
 
 
 * Menu:
 
 * exec-path:                             Emacs 27.1.          (line 228)
 * gensym-counter:                        Emacs 26.1.          (line  77)
 * lisp-directory:                        Emacs 29.1.          (line  17)
 * mounted-file-systems:                  Emacs 26.1.          (line 133)
 * regexp-unmatchable:                    Emacs 27.1.          (line 152)
 * set-transient-map-timeout:             Emacs 29.1.          (line 736)
 * text-quoting-style:                    Emacs 25.1.          (line  13)
 
 
 
 Tag Table:
 Node: Top829
 Node: Introduction2258
 Node: Overview2421
 Node: Usage2947
 Node: Limitations7326
 Node: Support12192
 Node: Emacs 25.112777
 Node: Emacs 26.122179
 Node: Emacs 27.139473
 Node: Emacs 28.159870
 Node: Emacs 29.179951
 Node: Development117330
 Node: Function Index119064
 Node: Variable Index134496
 
 End Tag Table
 
 
 Local Variables:
 coding: utf-8
 End: