root/linen/trunk/examples/math.rb

#!/usr/bin/env ruby
#
# Demonstrates a simple plugin that does basic math.
#
# == Authors
#
# * Ben Bleything <bbleything@laika.com>
#
# == Copyright
#
# Copyright (c) 2008 LAIKA, Inc.
#
# This code released under the terms of the BSD license.
#
# == Version
#
#  $Id$
#

require 'rubygems'
require 'linen'

class MathPlugin < Linen::Plugin
    description "Perform simple mathematical operations.  Currently supports addition, subtraction, multiplication, and division."

    floating_point_regex = /^\d+(\.\d+)?$/

    argument :lhs, 
             :prompt  => 'Please enter the left-hand operand: ',
             :regex   => floating_point_regex,
             :process => Proc.new {|i| i.to_f }

    argument :rhs, 
             :prompt  => 'Please enter the right-hand operand: ', 
             :regex   => floating_point_regex,
             :process => Proc.new {|i| i.to_f }

    command :add do
        help_message "Adds two operands. (lhs + rhs)"

        required_arguments :lhs, :rhs

        action do
            say "#{lhs} + #{rhs} = #{lhs + rhs}"
        end
    end

    command :subtract do
        help_message "Subtracts the second operand from the first. (lhs - rhs)"

        required_arguments :lhs, :rhs

        action do
            say "#{lhs} - #{rhs} = #{lhs - rhs}"
        end
    end

    command :multiply do
        help_message "Multiplies two operands. (lhs * rhs)"

        required_arguments :lhs, :rhs

        action do
            say "#{lhs} * #{rhs} = #{lhs * rhs}"
        end
    end

    command :divide do
        help_message "Divides the first operand by the second. (lhs / rhs)"

        required_arguments :lhs, :rhs

        action do
            say "#{lhs} / #{rhs} = #{lhs / rhs}"
        end
    end
end

Linen::CLI.prompt = "math > "
Linen.start