From: ahoward@... (ara howard)
Date: 2002-09-24T02:59:04+09:00
Subject: Re: alias/method redfinition

ts <decoux@moulon.inra.fr> wrote in message news:<rfcsn01ouju.fsf@moulon.inra.fr>...

so, in general, extending an object always results in a new proxy
class being created as the first one to be searched in the inheritence
hierarchy, and because mutiply extending an object with a module would
result in duplicate classes being created in the inheritence tree ruby
protects against this  by
not allowing 'extend M' to happen more than once?

-a


> a> this works.  though i do not understand how the super remains bound to
> a> the old [] after the call 'extend M'
> 
>  The new methods #[] and #[]= are created in the module M and they don't
>  erase the old definitions which are in the class Hash
> 
>  When you write
> 
>     extend M
> 
>  ruby will create a proxy class which is inserted just before the class
>  Hash, this will give a class (and methods) specific to this object
> 
>  When you call #[] (#[]=) for this object, ruby find these methods in the
>  proxy class, and with a call to #super ruby will retrieve the methods
>  stored in Hash
> 
>  You have something like this
>    * before extend, the inheritance for the object is
> 
>  Hash ==> [Enumerable] ==> Object ==> [Kernel]
> 
>    * after extend for this same object
> 
>  (singleton class) ==> [M] ==> Hash ==> [Enumerable] ==> Object ==> [Kernel]
> 
>  [M]          is a proxy class to M
>  [Enumerable] is a proxy class to Enumerable