From: elbows@... (Nathan Weston)
Date: 2003-12-06T04:22:03+09:00
Subject: Re: Using Modules as Decorators

Asfand Yar Qazi <im_not_giving_it_here@i_hate_spam.com> wrote in message news:<bqmkd5$eng$1@news8.svr.pol.co.uk>...
> Nathan Weston wrote:
> > Someone recently mentioned the idea of using Modules to implement the
> > Decorator pattern (though I can't find the post now, so maybe I
> > imagined it).
> 
> That was me.
> 
> However, this still doesn't solve my problem - you see, I need to also 
> be able to remove functionality from each object in addition to adding 
> it, and I don't think you can remove a module from an object once its 
> been added.
> 
> Perhaps a new feature in Ruby 2 perchance?

Yeah, not being able to undecorate objects is the big drawback to this
approach.
However, Object#dup doesn't copy singleton methods or modules included
with Object#extend, so you might be able to undecorate an object by
duping it.

Removable modules would be cool, but it would be tricky because
modules can use append_features and extend_object to perform arbitrary
transformations.

Nathan