From: Trans <transfire@...>
Date: 2009-02-16T11:02:17+09:00
Subject: Re: Exercise in Frustration



On Feb 15, 9:49 am, Pit Capitain <pit.capit...@gmail.com> wrote:
> 2009/2/15 Trans <transf...@gmail.com>:
>
> > Great. However, I also want the end-user of this library to be able
> > effect all classes and modules with a single extend (or include) as
> > well, if they so choose. Eg.
>
> >    class Module
> >      include MyEnhancement
> >    end
>
> Is the problem here that Module defines its own #attr_accessor
> shadowing the new one?

Yes, that's part of the issue here. In the case where one extends a
class, #super works, in the case of including it into Module, one had
to do the whole alias chaining thing.

As I worked on this it made me think that it would be nice if their
were a MetaKernel for the Module's methods, just as there is a Kernel
for Object's methods. That would at least DRY this part up.

> > It would also be nice if the module's methods can be made to work from
> > the toplevel (main):
>
> >   extend MyEnhancement
>
> What should #attr_accessor do in the context of the toplevel object?
> Maybe you can show us another example?

What it normally does, define a method wrapping an instance variable.
Having it at toplevel isn't that important in this case. But I have a
similar case for an original method (#annotator) where it is.

If the toplevel object were a self extended module, this would not be
an issue either. I know I've brought this up more than a few times,
but I don't recall Matz ever addressing it, and saying why it's not a
good idea. Sure wish I knew, with all the meta-coding I've done this
is one of the few issues I keep bumping my head against.

> > In attempting to implement this, I have found myself resorting to
> > unDRY, ugly, hacky code, that always seems to have a bug in it
> > somewhere. It's infuriating. This is not how programming Ruby is
> > supposed to be!
>
> Hmm, I think this will be hacky indeed.

Unfortunately, what I've managed to get to work very much is. You can
see my hacks for the real deal here:

http://anise.rubyforge.org/git?p=anise.git;a=tree;f=lib/anise;h=d64d5a9ecef1c1b8e1c76a7d84c8462f3aad7ee6;hb=HEAD

Thanks,
T.