Flag command line parsing in golang

Question

I'm not sure I understand the reasoning behind this example (taken from here), nor what it is trying to communicate about the Go language:

package main  import (     "flag"     "fmt" )  func main() {     f := flag.NewFlagSet("flag", flag.ExitOnError)     f.Bool("bool", false, "this is bool flag")     f.Int("int", 0, "this is int flag")      visitor := func(a *flag.Flag) {         fmt.Println(">", a.Name, "value=", a.Value)     }      fmt.Println("Visit()")     f.Visit(visitor)     fmt.Println("VisitAll()")     f.VisitAll(visitor)      // set flags     f.Parse([]string{"-bool", "-int", "100"})      fmt.Println("Visit() after Parse()")     f.Visit(visitor)     fmt.Println("VisitAll() after Parse()")     f.VisitAll(visitor) } 

Something along the lines of the setup they have but then adding a

int_val := f.get("int") 

to get the named argument would seem more useful. I'm completely new to Go, so just trying to get acquainted with the language.

Answer 1

This is complicated example of using flag package. Typically flags set up this way:

package main  import "flag"  // note, that variables are pointers var strFlag = flag.String("long-string", "", "Description") var boolFlag = flag.Bool("bool", false, "Description of flag")  func init() {     // example with short version for long flag     flag.StringVar(strFlag, "s", "", "Description") }  func main() {     flag.Parse()     println(*strFlag, *boolFlag) }