#--
# Credit goes to DHH.
#++

class Module

  # Creates a class-variable attr_reader that can
  # be accessed both on an instance and class level.
  #
  #   class MyClass
  #     @@a = 10
  #     cattr_reader :a
  #   end
  #
  #   MyClass.a           #=> 10
  #   MyClass.new.a       #=> 10
  #
  def cattr_reader(*syms)
    hsyms = ( syms.last.is_a?(Hash) ? syms.pop : {} )
    hsyms.update( Hash[*(syms.zip([nil]*syms.size).flatten)] )
    hsyms.each_pair do |sym, val|
      class_eval <<-EOS
        if ! defined? @@#{sym}
          @@#{sym} = val
        end
        def self.#{sym}
          @@#{sym}
        end
        def #{sym}
          self.class.#{sym}
        end
      EOS
    end
    return hsyms.keys
  end

  # Creates a class-variable attr_writer that can
  # be accessed both on an instance and class level.
  #
  #   class MyClass
  #     cattr_writer :a
  #     def a
  #       @@a
  #     end
  #   end
  #
  #   MyClass.a = 10
  #   MyClass.a            #=> 10
  #   MyClass.new.a = 29
  #   MyClass.a            #=> 29
  #
  def cattr_writer(*syms)
    hsyms = ( syms.last.is_a?(Hash) ? syms.pop : {} )
    hsyms.update( Hash[*(syms.zip([nil]*syms.size).flatten)] )
    hsyms.each_pair do |sym, val|
      class_eval <<-EOS
        if ! defined? @@#{sym}
          @@#{sym} = val
        end
        def self.#{sym}=(obj)
          @@#{sym} = obj
        end
        def #{sym}=(obj)
          self.class.#{sym}=(obj)
        end
      EOS
    end
    return hsyms.keys
  end

  # Creates a class-variable attr_accessor that can
  # be accessed both on an instance and class level.
  #
  #   class MyClass
  #     cattr_accessor :a
  #   end
  #
  #   MyClass.a = 10
  #   MyClass.a           #=> 10
  #   mc = MyClass.new
  #   mc.a                #=> 10
  #
  def cattr_accessor(*syms)
    m = []
    m.concat( cattr_reader(*syms) )
    m.concat( cattr_writer(*syms) )
    m
  end

end



#  _____         _
# |_   _|__  ___| |_
#   | |/ _ \/ __| __|
#   | |  __/\__ \ |_
#   |_|\___||___/\__|
#
=begin test

  require 'test/unit'

  class TCModule < Test::Unit::TestCase

    class MockObject
      def initialize
        @@a = 10
      end
      def b ; @@b ; end
    end

    def test_cattr_reader
      assert_nothing_raised {
        MockObject.class_eval { cattr_reader :a }
      }
      t = MockObject.new
      assert_equal( 10, t.a )
    end

    def test_cattr_writer
      assert_nothing_raised {
        MockObject.class_eval { cattr_writer :b }
      }
      t = MockObject.new
      t.b = 5
      assert_equal( 5, t.b )
    end

    def test_cattr_accessor
      assert_nothing_raised {
        MockObject.class_eval { cattr_accessor :c }
      }
      t = MockObject.new
      t.c = 50
      assert_equal( 50, t.c )
    end

  end

=end