Can't specify negative numbers for an int

[prashantv]

Example code:

type Options struct {
        Num int `short:"n" long:"num" description:"Number"`
}

func main() {
        var opts Options
        _, err := flags.Parse(&opts)
        if err != nil {
            log.Fatal(err)
        }

        fmt.Println("Num", opts.Num)
}

Works fine for 0/positive numbers:

$ ./flags -n 0
Num 0
$ ./flags -n 1
Num 1

But it fails for negative numbers, since it thinks the - is part of an options:

$ ./flags -n -1
expected argument for flag `-n, --num', but got option `-1'

This works fine with the standard library

var n = flag.Int("n", 0, "Num")

func main() {
        flag.Parse()
        fmt.Println("Num:", *n)
}

$ ./stdflags -n 0
Num: 0
$ ./stdflags -n 1
Num: 1
$ ./stdflags -n -1
Num: -1

[jessevdk]

Normally the answer is that this is not supported, if you want to pass anything as an argument starting with -, you need to use the -n=-1 syntax. However, I made an exception for numbers since it's relatively obvious what the user wants in that case.

[prashantv]

Thanks for the quick fix @jessevdk!