talks

print.go (1038B)

---

 package main
 
 import (
 	"fmt"
 	"sync"
 
 	"github.com/dwrz/talks/concurrency/pkg/weather"
 )
 
 const (
 	// Hardcoded padding for longest city name, Philadelphia.
 	message = "%-12s %.2f°F\n"
 )
 
 func printTemperatures(cities []string) {
 	for _, city := range cities {
 		cityWeather, err := weather.GetCity(city)
 		if err != nil {
 			fmt.Printf(
 				"error getting weather for %s: %v\n", city, err,
 			)
 			continue
 		}
 
 		fmt.Printf(message, city, cityWeather.Temp)
 	}
 }
 
 func printTemperaturesAsync(cities []string) {
 	var weatherReports = make(chan string, len(cities))
 	var wg sync.WaitGroup
 	wg.Add(len(cities))
 
 	for _, city := range cities {
 		go func(city string) {
 			defer wg.Done()
 
 			cityWeather, err := weather.GetCity(city)
 			if err != nil {
 				fmt.Printf(
 					"error getting weather for %s: %v\n",
 					city, err,
 				)
 				return
 			}
 
 			weatherReports <- fmt.Sprintf(
 				message, city, cityWeather.Temp,
 			)
 		}(city)
 	}
 
 	wg.Wait()
 	close(weatherReports)
 
 	for report := range weatherReports {
 		fmt.Print(report)
 	}
 }