How to get a list of values into a flag in Golang?

Question

What is Golang\'s equivalent of the below python commands ?

import argparse
parser = argparse.ArgumentParser(description=\"something\")
parser.add_argument(\         


        

Answer 1

Use flag.String() to get the entire list of values for the argument you need and then split it up into individual items with strings.Split().

Answer 2

You can at least have a list of arguments on the end of you command by using the flag.Args() function.

package main

import (
    "flag"
    "fmt"
)

var one string

func main() {
    flag.StringVar(&one, "o", "default", "arg one")
    flag.Parse()
    tail := flag.Args()
    fmt.Printf("Tail: %+q\n", tail)
}

my-go-app -o 1 this is the rest will print Tail: ["this" "is" "the" "rest"]

Answer 3

If you have a series of integer values at the end of the command line, this helper function will properly convert them and place them in a slice of ints:

package main

import (
    "flag"
    "fmt"
    "strconv"
)

func GetIntSlice(i *[]string) []int {
    var arr = *i
    ret := []int{}
    for _, str := range arr {
        one_int, _ := strconv.Atoi(str)
        ret = append(ret, one_int)
    }
    return ret
}

func main() {
    flag.Parse()
    tail := flag.Args()
    fmt.Printf("Tail: %T,  %+v\n", tail, tail)
    intSlice := GetIntSlice(&tail)

    fmt.Printf("intSlice: %T,  %+v\n", intSlice, intSlice)

}

mac:demoProject sx$ go run demo2.go 1 2 3 4
Tail: []string,  [1 2 3 4]
intSlice: []int,  [1 2 3 4]

Answer 4

You can define your own flag.Value and use flag.Var() for binding it.

The example is here.

Then you can pass multiple flags like following:

go run your_file.go --list1 value1 --list1 value2

UPD: including code snippet right there just in case.

package main

import "flag"

type arrayFlags []string

func (i *arrayFlags) String() string {
    return "my string representation"
}

func (i *arrayFlags) Set(value string) error {
    *i = append(*i, value)
    return nil
}

var myFlags arrayFlags

func main() {
    flag.Var(&myFlags, "list1", "Some description for this param.")
    flag.Parse()
}