From: Brian Candler <b.candler@...>
Date: 2011-03-03T07:23:56+09:00
Subject: Re: array of valid arguments in optparse

Ritesh Agrawal wrote in post #985009:
> I am trying to use optparse to parse an argument into an array and check
> for possible values. For instance consider an argument like this
>
> --operations count, count+, count-
>
> I want to parse above argument into @options[:operations] = ["count",
> "count+", "count-"].

Well, the spaces will cause the shell to split it; the user will 
probably need to type

--operations count,count+,count-

or

--operations "count, count+, count-"

If you look at the source code for optparse.rb you'll find an example of 
list arguments:

#         # List of arguments.
#         opts.on("--list x,y,z", Array, "Example 'list' of arguments") 
do |list|
#           options.list = list
#         end

> But at the same time I have limited vocabulary for
> possible operations and I want to check for that so that if some gives
> any other operation argument, it throws an error message

Just throw the error yourself.

OPERATIONS = ["count", "count+", "count-"]

opts.on ... do |hypo|
  raise OptionParser::InvalidArgument, "Invalid operation" unless (hypo 
- OPERATIONS).empty?
end

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