From: Todd Benson <caduceass@...>
Date: 2008-05-17T08:04:34+09:00
Subject: Re: Monkey Patching (definition)?

On Fri, May 16, 2008 at 3:20 PM, ThoML <micathom@gmail.com> wrote:
>> There was a long discussion on the topic in this thread:
>> <http://groups.google.com/group/ruby-talk-google/browse_thread/thread/...>
>
> And there even is a wikipedia article on MP:
> http://en.wikipedia.org/wiki/Monkey_patching

Interesting side note:

class C
  def foo obj
    'foo ' << obj.to_s
  end
end

c = C.new

class C
  unless respond_to?('foo')
    def foo obj
      'bar ' << obj.to_s
    end
  end
end

class Array
  unless respond_to?('==')
    def == obj
      'arr == ' << obj.to_s
    end
  end
end

puts c.foo(42)
# bar 42 -- the new method ran over the old one
puts [] == 42
# false -- the new method was ignored


The parser doesn't check the unless condition for 'normal' methods.
(This is on 1.8.6)

Todd