From: Jeff Rose <rosejn@...>
Date: 2006-05-24T03:07:34+09:00
Subject: Re: initializing instance variables in a module

> This thread seems to have gone astray a bit but I didn't see this
> solution which I regard the standard way to handle this. The important
> part is to use initialize(*a,&b) in the module. I've put this on the
> wiki for easier reference:
> 
> http://wiki.rubygarden.org/Ruby/page/show/InitializingWithInheritance
> 
> Kind regards
> 
> robert

This doesn't really solve the problem.  The idea is that you don't want 
the including class to have to do anything related to initialization of 
the module(s) being included.  In your example any including class would 
have to call super in order to make it work.  If Derived implements an 
initialize method and doesn't call super then the module isn't 
initialized.  But why should it call super, it isn't deriving from 
anything, it is mixing it in.

The two options Matz mentioned are the way to go.  Either a callback 
(module_initialize), which will act as an initialization method for the 
module, or the ability for the module to insert its own method(s) 
before, after, or around the class that includes it.  (CLOS method 
combinations...  AOP)

-Jeff