From: Robert Dober <robert.dober@...>
Date: 2007-09-07T03:54:01+09:00
Subject: Re: before, after and around Ruby 1.9

On 9/6/07, Trans <transfire@gmail.com> wrote:
>
>
> On Sep 5, 6:46 pm, Yukihiro Matsumoto <m...@ruby-lang.org> wrote:
> > Hi,
> >
> > In message "Re: before, after and around Ruby 1.9"
> >     on Thu, 6 Sep 2007 10:32:03 +0900, Joel VanderWerf <vj...@path.berkeley.edu> writes:
> >
> > |What if you want to reopen _without_ the "around" semantics?
> >
> > I thought we need to remove the previous one first.
> >
> > |Could we have these two variations:
> > |
> > |class Foo < Foo       # <-- This is a type error in 1.8
> > |   def foo; super; end # AROUND
> > |end
> > |
> > |class Foo
> > |   def foo; super; end # REDEFINE
> > |end
> > |
> > |At least that is a conservative extension.
> >
> > Or maybe providing two supers, one for the current behavior, the other
> > for the new.  I don't whatever name is suitable for new super yet,
> > however.
>
> How would you be sure (and why would you want to?) know when a
> "previous" exists or not? It rarely make sense to avoid advice.
> However, when absolutely needed one can fallback to directed calling
> with things like:
>
>   super_at(Object)
Inheritance dependecies, oooouch, danger, hot do not touch!
Mixin dependecies even worse imagine you want to refer to a mixed in
method, maybe it was mixed in by an anonymous module, or the method
was defined at instance level.

After all it feels wrong to have around, before and after built into
the language, this seems to be a job for the metaprogrammers not for
Matz.
I'd prefer having an easy way to do this with metaprogramming and then
put the implementations into the library.

if there were a method object tree rather than a stack  and if each
method object just had references to the defining Module/Singleton
Module, would we not be *very* happy?

module A
   def a; 222 end
end
module A
   def a; 132 end
end
class B
   include A
   def a; 110 end
end
class C < B
   def a; 60 end
end

class C
   include Module::new{ def a ; 52 end }
end


c = C.new
ma = c.method :a
ma = ma.unbind
ma.bind(c).call => 52
ma.old.bind(c).call => 60
ma.super.bind(c).call => 110
and most importantly

D= Class::new {
    define_method :a { -3 + ma.bind(self).call - 3 }
}
D.instance_method(:a).old == ma => true


Cheers
Robert
>
> or
>
>   as(Object).foo
>
> T.
>
>
>


-- 
I'm an atheist and that's it. I believe there's nothing we can know
except that we should be kind to each other and do what we can for
other people.
-- Katharine Hepburn