From: Gavin Sinclair <gsinclair@...>
Date: 2004-03-25T05:51:24+09:00
Subject: Re: optparse and required options

On Thursday, March 25, 2004, 2:54:28 AM, Jim wrote:

> I'm just starting to use optparse. I want to force the user to supply an
> option. How can I do this with optparse? Here's what I have

> email = nil
> ARGV.options { | opt |
>     opt.on('-e', '--email EMAIL', EMAIL address') { | e | email = e }
>     opt.parse!
> }

> This forces the '--email' option to take an argument. What I want to do is
> force the user to supply an '--email EMAIL' option.

> Do I have to append

>     usage() if email.nil?

> and if so, how do I get the optarg obejct's help message?

> Thanks for your help.

Here are my idioms:

  def show_help(parser, code=0, io=STDOUT)
    io.puts parser
    exit(code)
  end

  o = options = OpenStruct.new
  parser = OptionParser.new do |p|
    # ...
    p.on('-e', '--email ADDRESS', 'Send email to ADDRESS') do |a|
      o.operation = :email
      o.address = a
    end
    # ...
    p.on('-h', '--help', 'Show this message') do
      show_help(p)
    end
  end

  parser.parse!(ARGV)

  if o.operation.nil?
    show_help(parser, 1, STDERR)
  end

  
Hope this helps,
Gavin