From: Daniel Brockman <daniel@...>
Date: 2005-07-04T04:06:20+09:00
Subject: Re: warning: refine foo, what!?

"_ugly" <mgarriss@gmail.com> writes:

> class << o
>    undef_method :foo
> end

[...]

> # undef_method_test.rb:8: warning: redefine foo
>
> Is my head broken or ruby -W broken?  I'm thinking the former.

It's not that simple, because `undef_method' doesn't remove methods;
it overrides them with empty, or ``undefined'' ones.

   void
   rb_undef_method(klass, name)
       VALUE klass;
       const char *name;
   {
       rb_add_method(klass, rb_intern(name), 0, NOEX_UNDEF);
   }

Thanks to that, you can do stuff like this:

   class Foo ; undef_method :dup end
   Foo.new.dup
   NoMethodError: undefined method `dup' for #<Foo:0x402a12b0>

I think you are looking for `remove_method'.

   $ ruby -W
   bar = Object.new
   def bar.foo ; end
   class << bar ; undef_method :foo end
   def bar.foo ; end
   -:4: warning: redefine foo

   $ ruby -W
   bar = Object.new
   def bar.foo ; end
   class << bar ; remove_method :foo end
   def bar.foo ; end

-- 
Daniel Brockman <daniel@brockman.se>

    So really, we all have to ask ourselves:
    Am I waiting for RMS to do this?   --TTN.