gistfile1.txt

module ResultCaching
  def with_result_caching
    begin
      @methods_to_cache = []
      @caching = true
      yield
      @caching = false
      @methods_to_cache.each do |name|
        alias_method "cached_#{name}", name
        class_eval <<-EOF
def #{name}
  @#{name} ||= send :cached_#{name}
end
EOF
      end
    ensure
      @methods_to_cache = nil
      @caching = false
    end
  end
  
  def method_added(name)
    if @caching
      @methods_to_cache << name
    end
    super
  end
end

class Foo
  extend ResultCaching
  
  with_result_caching do
    def bar
      @count ||= 0
      @count += 1
    end
  end
end

foo = Foo.new
puts foo.bar
puts foo.bar