From: "T. Onoma" <transami@...>
Date: 2003-11-27T15:45:46+09:00
Subject: Re: Method wrapping

On Thursday 27 November 2003 12:32 am, Yukihiro Matsumoto wrote:
> responsibility to define Ruby2 behavior:
> |1. Is it possible to add multiple wrappers for a method or
> |not? Do they "stack"?
>
> They stack.
>
> |2. If they do stack, is it possible to redefine a method as we
> |are used to doing? Or will that simply add a new wrapper?
>
> Re-defining primary method (method without :pre, :post, or :wrap)
> replaces old primary methods.

I would like to point out that their is some inconsistentcy in this behavior, 
in that def behaves differently depending on whether it is defined in class 
augmentation or a subclass.

  class A < X
    def riot
      super
      print "P"
    end
  end

  class A
    def riot          # this redifines
      super
      print "R"
    end
  end

  class B < A
    def riot
      super           # this wraps
      print "W"
    end
  end

The def syntax is the same but each has different semantic meaning (effects 
code readability/code maintainence).

It is important to understand that Ruby already has a wrapping facility using 
subclasses. And singletons act similiarly. So it would be more consistent to 
naturally extend that to in-class wraps. We can do this without having to add 
special syntax sugar (the colon).

Furthermore, from what I can tell, the current proposal does not address super 
wrapping. An issue have delt with in my AOP work.

Please refer to:

  http://www.rubygarden.org/ruby?AspectOrientedRuby

for more information on all this.

-t0