From: Florian Gross <flgr@...>
Date: 2004-12-21T18:57:05+09:00
Subject: Re: Dynamic Methods not Behaving as Expected

Marc Merlin wrote:

> Motivation: I would like to create an "imposter" class that supports the
> definition of dynamically-defined methods.  Once defined, these dynamic
> methods should be invokable as though they were garden-variety
> statically-defined methods.
> 
> Problem: The dynamic methods implemented in the following code (and other
> work-arounds I've tried) don't seem to exhibit the exact same behavior as
> their static counterparts.  In particular, blocks attached at the point of
> method invocation don't seem to be detected.

Unfortunately .define_method can not be used to define methods with 
blocks before Ruby 1.9 because blocks have no block slots.

You can workaround that by doing this:

   create_wrapper = lambda do |name|
     instance_eval %{
       def #{name}(*args, &block)
         #{name}_block(block, *args)
       end
     %}
   end

   define_method(:foo_block) { |block, *args| puts "foo!" }
   create_wrapper.call(:foo)

It's not the most beautiful thing of the world but at least it can be 
abstracted away easily...