From: "T. Onoma" <transami@...>
Date: 2003-11-23T17:30:33+09:00
Subject: Re: Method wrapper question (was "stereotyping (was ...))

After some exhaustive research and endless hours of thought I have put 
together a page at RiteSuggestions about Aspect Oriented Programming (AOP) 
for Ruby. (AOP is the overall term for programming with join-points which is 
what :pre, :post and :wrap represent.) Have a look at.

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

As always, typo fixes and comments are welcome.

-t0

On Sunday 23 November 2003 09:02 am, Ryan Pavlik wrote:
> On Sat, 22 Nov 2003 23:33:57 +0900
>
> "Christoph" <chr_mail@gmx.net> wrote:
> > ts wrote:
> > ...
> >
> > >  Yes, and this is why I prefer this scheme to
> > >
> > >    class A
> > >       def a:pre
> > >       end
> > >
> > >       def a:pre
> > >       end
> > >
> > >       def a
> > >       end
> > >    end
> >
> > Agreed 100% - I see no reason for allowing several hooks in the same
> > class.
> >
> > /Christoph
>
> Hmm, actually, there are a lot of good reasons for allowing multiple
> hooks in the same class.  This is, AFAIK, the point of having hooks at
> all... so many people can hook into them.
>
> For instance, you may add a method:pre hook to check some parameter
> values, make sure they're in range.  You may include a package which
> adds a :pre hook to add permissions.  Etc.
>
> If you can only have one hook, what's the difference between doing
> this:
>
>     class Foo
>        def bar:pre
>          # pre stuff
>        end
>
>        def bar
>          # body stuff
>        end
>     end
>
>
> and doing this:
>
>     class Foo
>        def bar
>          # pre stuff
>          # body stuff
>        end
>     end
>
> or even this:
>
>     class Foo
>        def bar_pre
>          # pre stuff
>        end
>
>        def bar
>          bar_pre
>          # body stuff
>        end
>     end
>
> To answer the question of order, it can either be configurable (I
> think CLOS allows this) or simply "stack order" (latest defined :pre
> goes first, latest defined :post goes last, etc.).