From: Josh Cheek <josh.cheek@...>
Date: 2010-03-21T14:23:58+09:00
Subject: Re: A plugin system using extend

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On Sat, Mar 20, 2010 at 9:46 PM, Jean-denis Vauguet <jd@vauguet.fr> wrote:

> Hi.
>
> I tried to design a simple plugin system using :extend called upon
> instance (http://ruby-doc.org/core/classes/Object.html#M000335 usual
> documented behavior), so as to inject some methods redefinitions while
> keeping the ability to call super in order to fall back on the default
> behavior if needed.
>
> It looks like this: http://gist.github.com/339025
> It works as expected, as one can see by reading the commented output at
> the end of the file: the inheritance chain is altered, with the plugin
> "subclassing" the original class of the plugin receiver.
>
> Yet, I tried to introduce some modularity in the system, so I went for:
> http://gist.github.com/339028
> It fails but I don't understand why. The inheritance chain is not
> altered.
> I tried to use :include instead of :extend, which gives merely the same
> behavior (overwriting instance methods), but this time the plugin module
> is added as the parent of the original class within the inheritance
> chain, so it is useless for the purpose ;)
>
> I'll be glad if someone could give me a hint on this :)
> Thank you!
> --
> Posted via http://www.ruby-forum.com/.
>
>
Hi, I got it to do what I think you are looking for by having plugins pass
the object to extend. http://gist.github.com/339101
To test it, I had the redefined object say things in reverse. I also added
another module to show that you can activate different behaviours in
different objects.

Then I played around with it a little bit more, trying to make it more
modular, and behave similar to ActiveRecord's scopes
http://gist.github.com/339114

I wanted to try to make the plugin agnostic to the method it was activating
so that you could, for example, make a plugin that could then be applied to
any method of any object. But I just can never seem to get define_method to
work right -.- every time I try to do that, I seem to struggle a lot with
it, and usually end up using eval with a string, because dynamically adding
a method is so difficult.

Oh well, I'm kind of happy with it.

Guess I should pick up PragProg's Metaprogramming Ruby book... or try out
Lisp >:D

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