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From: alfh@gyda.ifi.uio.no (Alf-Ivar Holm)
Newsgroups: comp.lang.beta
Subject: Re: Adding methods without renaming the class (was Re: What's wrong with this picture?)
Date: 28 Dec 1995 14:21:43 +0100
Organization: Dept. of Informatics, University of Oslo, Norway
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Message-ID: <wog68f1xr15.fsf@gyda.ifi.uio.no>
References: <4aodps$70h@netnews.upenn.edu>
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In-reply-to: Wolfgang Ziller's message of 24 Dec 1995 22:02:19 GMT
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In article <4bkilb$g47@netnews.upenn.edu> Wolfgang Ziller <wziller@math.upenn.edu> writes:

> olevi@daimi.aau.dk (Ole Villumsen) wrote:
> >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.
> 
> However, the FAQ (v. 1.7) says that this is not possible
> with the current compiler since certain ambiguities come up
> by doing that.  To (partially) solve the problem, one is
> allowed to write <<slot myClassLib: attributesDecl>> which 
> only allows *one* attribute to be added.
> 
> Has this problem been fixed in the current implementation 
> or is the limitation still in place?

F08 in the FAQ refers to the grammar, not the compiler.  The fragment
system is part of the implementation and has an alias between
<attributes> and <attributesDecl>, i.e. the above is possible.  

(On the other hand, I don't know why the grammar would be ambiguous if
<attributes> were allowed to generate itself.)

	Affi