monkey-proof.rb

# require 'monkey-proof'
#
# class Foo
#   def foo() puts 'foo'; end
# end
# monkey_proof Foo
#
# class Foo
#   include Enumerable
# end
# => TypeError: can't modify frozen object
#
# foo = Foo.new
# foo.extend Enumerable
# => TypeError: can't modify frozen object
#

module MonkeyProof

  VERSION = '1.0.0'

  def self.included( other )
    return if other.frozen?

    if Class === other
      other.instance_eval <<-CODE
        def new( *args, &block )
          i = super
          class << i; self.freeze; end
          return i
        end
      CODE
    end
    other.freeze
  end

  def self.extended( other )
    if Module === other
      included other
    else
      class << other; self.freeze; end
    end
    other
  end

end  # module MonkeyProof

module Kernel
  def monkey_proof( obj )
    MonkeyProof.extended obj
  end          
end