From: Ryan Pavlik <rpav@...>
Date: 2003-11-22T09:03:40+09:00
Subject: Method combination

On Sat, 22 Nov 2003 08:37:03 +0900
matz@ruby-lang.org (Yukihiro Matsumoto) wrote:

> 
> |An aside: Unfortunately, the post method doesn't have access to the result
> |returned from the function.  In this case it doesn't matter, but many post
> |conditions assert something interesting about the result.  I guess I would
> |have to use a wrap method for that.
> 
> The only reason the result is _not_ available from post method is we
> don't have neat syntax construct.  Any proposal?
> 
> 							matz.

Lisp has (call-next-method &rest args) used in method combination...
I'm not sure how things have been proposed (I only saw the slide),
but:

  def foo:pre(a,b)
    call_next unless (a > b)
  end

  def foo(a, b)
    return "OK" if (a < 15)
    call_next(a+b)
  end

  def foo:post(x)
    :
  end

  def foo:wrap(a,b)
    # blah blah
    res = call_next(b, a)   # Might get "OK"? or whatever :post returns..
    # blah blah
  end

Again, I'm not sure how you want everything to flow exactly.  With
'call_next', the ability to call it or not is both an advantage and a
disadvantage.

-- 
Ryan Pavlik <rpav@mephle.com>

"Now if you'll excuse me, I've got to single-handedly
 save a film genre." - 8BT