Comparing version numbers with Ruby

require 'revision'
if Revision.new('1.0.10') > Revision.new('1.0.2')
  puts "1.0.10 > 1.0.2"
end

#!/usr/local/bin/ruby -w

# Revision class
# Designed to function in version comparisons, where the
# version number matches /\d+(\.\d+)*/

# Author: Hugh Sasse, De Montfort University <hgs@dmu.ac.uk>

# Created: 06-OCT-2000
# Last Modified: 13-APR-2010

class Revision

    attr :contents

    def to_i
	@contents.collect { |j| j.to_i }
    end

    def to_s
	astring = @contents.collect { |j| j.to_s }
        astring.join(".")
    end

    def <(x)
       comparison = @contents <=> x.contents
       case comparison
           when -1
               result = true
           when 0
               result = false
           when 1
               result = false
       end
       result
    end

    def >(x)
       comparison = @contents <=> x.contents
       case comparison
           when -1
               result = false
           when 0
               result = false
           when 1
               result = true
       end
       result
    end

    def ==(x)
       comparison = @contents <=> x.contents
       case comparison
           when -1
               result = false
           when 0
               result = true
           when 1
               result = false
       end
       result
    end


    def initialize(thing)
        if thing.class == Revision
		@contents = thing.contents.dup
		# dup so we get a new copy, not a pointer to it.
	elsif thing.class == String
		result = thing.split(".").collect {|j| j.to_i}
		@contents = result
	elsif thing.class == Float
		@contents = thing.to_s.split(".").collect {|j| j.to_i}
	else
                raise "cannot initialise to #{thing}"
        end
    end

end

if __FILE__ == $0

    # Perform RubyUnit tests

    require "runit/testcase"
    require 'runit/cui/testrunner'
    require 'runit/testsuite'

    class  Testing_class < RUNIT::TestCase
        def test_a
            a = Revision.new("1.2.3")
            assert_equal([1,2,3], a.contents, "initialize failed #{a.contents}")
            a = Revision.new("2.4.8")
            b = Revision.new(a)
            assert_equal([2,4,8], b.contents, "initialize failed #{a.contents}")
            a = Revision.new(2.3)
            assert_equal([2,3], a.contents, "initialize failed #{a.