May be you should read the PhD of alex since it was about scoping  
class extension.

After thinking of lot another solution can be as in objective-C (I  
may be wrong) to support class extension
but not method redefinition.

Another approach could be selector namespace, since your changes are  
only local in your context, and you can still
have all the power of class extension.

If you read the OOPSLA paper on classbox you can see why subclassing  
does not work and why Swing has serious problems.

Stef

On 1 mars 07, at 11:41, Andreas Raab wrote:

> giorgioferraris at elevensoft.it wrote:
>> VW allow parcel to modify a method already on the image.  
>> Interesting behavior is the fact that, if and when you remove the  
>> parcel (thing you can do on a running application) the  
>> modification goes away, and the old behavior get restored.
>
> That's what I expected.
>
>> This seems to me more on the Smalltalk stile of thinking: I can do  
>> what I want, obviously also shut at my foot.
>
> Well, that's great as long as it is *your* foot. Unfortunately,  
> when modifying a base class that other modules use you are not  
> shooting your own foot - you are shooting the *other* guys foot  
> (since your module will work happily with those modifications but  
> the other modules won't) and that's not okay for a module system.
>
> Cheers,
>   - Andreas
>
>