a nice and simple version class

version.rb

class Version < ::String
  class Error < ::StandardError; end

  attr :major
  attr :minor
  attr :teeny

  def Version.default
    Version.for('0.0.0')
  end

  def Version.for(*args)
    version = args.size == 1 && args.first

    case version
      when Version
        version
      else
        Version.new(*args)
    end
  end

  def Version.numbers(version)
    Version.for(version).numbers
  end

  def initialize(*args, &block)
    super(args.flatten.join('.'))
  ensure
    @major, @minor, @teeny = strip.split(/\./).map{|v| v.to_i}
  end

  def <=> other
    numbers <=> Version.for(other).numbers
  end

  def numbers
    [major, minor, teeny]
  end

  %w( major minor teeny ).each do |number|
    module_eval <<-__, __FILE__, __LINE__

      def bump_#{ number }!
        @#{ number } += 1
        replace(numbers.join('.'))
        self
      end

      def bump_#{ number }
        dup.bump_#{ number }!
      end

    __
  end

  alias_method('bump', 'bump_minor')
  alias_method('bump!', 'bump_minor!')
end

SomeClass.for, in my code, nearly always conforms to the following interface:

"given a bucket of random arguments, do your best to make a choice at how to call 'new' with them. as a special case, iff the object is already of the class in question, simply return it"

it's a sort of cast-or-build factory that let's me do things like #L34 without needing to worry about making lots of extraneous objects. a more sophisticated example: https://github.com/ahoward/map/blob/master/lib/map.rb#L42 - note that this one even works for class Foo < ::Map...

some other examples:

• https://github.com/ahoward/upload_cache/blob/master/lib/upload_cache.rb#L198
• https://github.com/ahoward/configuration/blob/master/lib/configuration.rb#L17

I'm totally in for that - but I've reverted to the Gem::Version class since in 99 percent of the cases it's there for me anyway. Like here https://github.com/julik/update_hints/blob/master/lib/update_hints.rb#L28

using Gem::Version is a good idea. in my case i really needed domain specific '@version.bump!'