Disable placeholder

[p3lim]

If placeholder is set to an empty string, don't show it.

Example:

package main

import "github.com/alexflint/go-arg"

type args struct {
	Example string `arg:"-e" placeholder:"" help:"foo"`
}

func main() {
	var args args
	arg.MustParse(&args)
}

Expected result:

Usage: arg [--example]

Options:
  --example, -e          foo
  --help, -h             display this help and exit

Actual result:

Usage: arg [--example ]

Options:
  --example , -e         foo
  --help, -h             display this help and exit

[alexflint]

Seems reasonable but out of interest why would you put a struct tag with an empty string for the placeholder in the first place?

[p3lim]

Better example why I want to hide the placeholders:

Before:

Usage: arg [--config CONFIG] [--output OUTPUT] [--key KEY] [--quiet]

Options:
  --config CONFIG, -c CONFIG
                         help me
  --output OUTPUT, -o OUTPUT
                         help me
  --key KEY, -k KEY      help me
  --quiet, -q            help me
  --help, -h             display this help and exit

After:

Usage: arg [--config ] [--output ] [--key ] [--quiet]

Options:
  --config , -c          help me
  --output , -o          help me
  --key , -k             help me
  --quiet, -q            help me
  --help, -h             display this help and exit

The placeholder just destroys the readability of the help section (in my opinion at least), and this was only a small example.

[p3lim]

I could live with them if the options ended up like this though:

Usage: arg [--config CONFIG] [--output OUTPUT] [--key KEY] [--quiet]

Options:
  --config, -c CONFIG   help me
  --output, -o OUTPUT   help me
  --key, -k KEY         help me
  --quiet, -q           help me
  --help, -h            display this help and exit

This seems to be the norm with long and short option variants, which go-arg doesn't follow.

[alexflint]

Ah very good point!