version_info.rb

1-version_info.rb

require 'version_info/data'
require 'version_info/tasks'

module VersionInfo

  # current segments or defaults
  def self.segments
    @segments ||= [:major, :minor, :patch] 
  end

  # define segments
  def self.segments=(values)
    @segments = values
  end
   
  def self.included(other)
    other.const_set('VERSION', Data.new)
  end

end

2-tasks.rb

module VersionInfo 
  class Tasks

    def self.install(klass, opts = {})
      self.new(klass,  opts).install
    end
    
    attr_reader :target

    def initialize(klass, opts)
      @target = opts.delete(:class)
      self.extend(self.class.const_get(klass.to_s))
      self.configure(opts)
    end

    module Rake
      attr_reader :root_path

      def configure(opts={})
         self.extend Rake::DSL   # have to check if this would work
         # set up the root_path, etc.
      end 

      def install
         # same as you have it
      end
    end

    module Thor
      def configure(opts={})
         # nothing needed here?
      end

      def install      
        Class.new(::Thor) do
        
          desc 'show', "Show version tag and create version_info.yml if missing"
          def show
            puts target::VERSION.tag
            target::VERSION.save unless File.exist?(target::VERSION.file_name)
          end

          #etc.
        end
      end

    end

  end
end

4-Thorfile

VersionInfo::Tasks.install :Thor, :class => MyProject

5-Rakefile

VersionInfo::Tasks.install :Rake, :class => MyProject