simple_cli.rb

#!/usr/bin/env ruby
# simple_cli.rb

=begin rdoc
Parses command line options.
=end
class SimpleCLI

  # CONSTANTS

  OPTIONS = {
    :version => ['-v', '--version'],
    :help    => ['-h', '--help'],
    :reset   => ['-r', '--reset'],
  }

  USAGE =<<END_OF_USAGE

This program understands the following options:
  -v, --version : displays the current version of the program
  -h, --help    : displays a message with usage instructions
  -r, --reset   : resets the program

With no command-line options, the program performs its default behavior.

END_OF_USAGE

  VERSION = "Some Project version 0.01 (Pre-Alpha)\n"

  # METHODS

  def parse_opts(args)
    return option_by_args(args[0]) if understand_args?(args)
    # options are not understandable, therefore display_usage
    display(USAGE) 
  end

  private

  def display(content)
    puts content
  end

  def do_default()
    puts 'I am performing my default behavior'
  end

  def option_by_args(arg)
    return display(VERSION) if OPTIONS[:version].include?(arg)
    return display(USAGE)   if OPTIONS[:help].include?(arg)
    return reset()          if OPTIONS[:reset].include?(arg)
    do_default()
  end

  def reset()
    puts 'I am resetting myself.'
  end

  def understand_args?(args)
    # works in Ruby1.8
    OPTIONS.keys.any? { |key| OPTIONS[key].include?(args[0]) }
    
=begin works in Ruby1.6
    return true unless args
    return true unless args[0]
    return true if args[0].size.zero?
    OPTIONS.keys.each do |key| 
      return true if OPTIONS[key].include?(args[0])
    end
    return false
=end
  end

end