From: Joel VanderWerf <vjoel@...>
Date: 2007-05-20T05:36:18+09:00
Subject: Re: Block Trouble (Binding Issue?)

Pieter V. wrote:
> I'm presently trying to work on a little metaprogramming project, but
> am finding my efforts a little frustrated by ... well, I'm not rightly
> sure what by.  It seems to be a scoping issue, from what I can tell.

Yup, it sure is. define_method(name, &block) changes the scope of block 
to the instance, but the yield still references a block in class Foo scope.

A fix might be to replace yield with instance_eval(&b), as below, but 
that will preclude passing arguments to the block, in case you ever need 
to do that. Google for instance_exec for a discussion, hacks for the 
present, and hope for the future (1.9 has it)...

>  def self.special_meth(name, &b)
>    meth(name) do
>      # do something special
>      yield # <= This is the problematic call
        instance_eval(&b)
>    end
>  end
> end

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407