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From: sommar@enea.se (Erland Sommarskog)
Newsgroups: comp.lang.eiffel
Subject: Multiple creation routines.
Message-ID: <2295@enea.se>
Date: 8 Dec 90 22:11:55 GMT
References: <4106@tantalum.UUCP> <1045@tetrauk.UUCP> <4212@tantalum.UUCP>
Organization: Enea Data AB, Sweden
Lines: 37

Also sprach Tom H. Meyer (tom@ozmium.UUCP): (he is also >>>)
>In article <1045@tetrauk.UUCP> Rick Jones (rick@tetrauk.UUCP) writes:
>>>I dislike this on the grounds that it would *require* that 'Create' be a
>>>keyword. I hope to see the day when classes can have more than one
>>>creation routine and this seems to disallow it.
>>
>>Of course Create currently IS a keyword in effect.  The idea of multiple
>>creates is interesting, but if you needed them, would they not be
>>differentiated by their parameters?
>
>Not necessarily. It's easy for me to envision two different creation routines
>that had identical interfaces.

Wait guys! Dr. has Meyer already announced this as a coming
change in Eiffel 3.0. I just dug up the article in my binder.

In short there is first a new clause:

    CREATION f, g, h ....

listing all routines which can create an object.

You create an object with

       x !D! f(...);

where x is of type C and D is a descendant of C. f is a creation
procedure of D. D is optional, the default being C. If D contains
no creation statement breaks down to

      x !!

(I have to admit that I don't like this syntax. I prefer words
instead of symbols, but it's not me who is the langauge designer,
and I know that Dr. Meyer has another opinion.)
-- 
Erland Sommarskog - ENEA Data, Stockholm - sommar@enea.se