Path: news.daimi.aau.dk!olevi
From: olevi@daimi.aau.dk (Ole Villumsen)
Newsgroups: comp.lang.beta
Subject: Adding methods without renaming the class (was Re: What's wrong with this picture?)
Date: 20 Dec 1995 15:40:40 GMT
Organization: DAIMI, Computer Science Dept. at Aarhus University
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Message-ID: <4b9apo$aop@krone.daimi.aau.dk>
References: <4aodps$70h@netnews.upenn.edu> <4b6p2p$dua@fbi-news.Informatik.Uni-Dortmund.DE>
NNTP-Posting-Host: indium.daimi.aau.dk

Wilfried Rupflin <wr@polly.informatik.uni-dortmund.de> writes:

>>One language question (which I need answered in order to 
>>compare Dylan and BETA -- I'm still not sure which to go 
>>with).  Is it possible to add methods to a class without 
>>having to rename the class.  I would think yes since 
>>extension of patterns is allowed.
>>
>You are right in the case of virtual classes:

>  A_class:         (# my_class:<  (# a: ... #); ... #);

>  B_class: A_class (# my_class::< (# b: ... #); ... #);

There's another possibility: using an attributes slot.

myClass: (# <<slot myClassLib: attributes>>

            methodA: (# ... #)
            ...
         #);

Such a slot allows you to define in a different fragment, additional
methods for myClass, even if myClass is written by someone else,
frozen and delivered to you.

Ole V.