From: Avi Bryant <avi@...4.com>
Date: 2001-03-06T13:02:41+09:00
Subject: [ruby-talk:12082] Re: ANN: Memoize 0.1.2


I think the problem is that I always use rb_iterate to make the call;
that is, I do

call {yield}

when I should do

if block_given?
  call {yield}
else
  call
end

Should be easy enough to fix.

On Tue, 6 Mar 2001, Robert Feldt wrote:

> On Tue, 6 Mar 2001, Avi Bryant wrote:
> 
> > So somehow I'm messing up the block_given? call; I'm not sure how.
> > Ideas, anyone?
> > 
> Yes, its kind of strange that it is messed up.
> My interpretation of what your trying to do with advice.c is (in Ruby
> code with generality taken away):
> 
> ---
> def orig
>   puts "hello world"
>   puts block_given?
> end
> 
> def real_call(&b)
>   Object.send(:orig)
> end
> 
> def call_method
>   real_call {yield}
> end
> 
> def call_advice(&b)
>   advice(&b)
> end
> 
> def advice
>   puts "pre"
>   yield
>   puts "post"
> end
> 
> def dispatch
>   call_advice {call_method}
> end
> 
> dispatch
> ---
> 
> Is that a correct interp?
> 
> (BTW, I'm not sure I understand the need for real_call and call_method
> with the yield. Cant they be merged? Or will it not work when we want to
> alter what is returned from the advice?)
> 
> The above code works and does not mess up the block_given? call. I guess
> the problem might be in a difference between in how rb_iterate handles the
> iter stack as opposed to when the above Ruby code is executed. But my
> knowledge of Ruby internals is too limited. Matz or Guy or any other one?
> 
> /Robert
>