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From: bertrand@eiffel.UUCP (Bertrand Meyer)
Newsgroups: comp.lang.eiffel
Subject: Re: Multiple creation routines.
Summary: No semantic change
Message-ID: <465@eiffel.UUCP>
Date: 19 Dec 90 03:16:02 GMT
References: <4106@tantalum.UUCP> <1045@tetrauk.UUCP> <4212@tantalum.UUCP> <1057@tetrauk.UUCP>
Organization: Interactive Software Engineering, Santa Barbara CA
Lines: 29

From <1057@tetrauk.UUCP> by rick@tetrauk.UUCP (Rick Jones) on the
new syntax for creation:


> I have one query though.  The proposed syntax allows an object to be created
> using the form:

> 	x !!

> meaning create an "empty" object.  It may be quite incorrect for an object of
> the class in question to be in such a state - i.e. the invariant would be
> violated.  [...]. This is a retrograde step from the current
> situation, where a call to the create routine at least has to provide the
> proper arguments.

> It would seem that the "creation" clause needs some way of specifying whether a
> default creation call is valid or not.


	The above form is only valid if the class has no creation routine.
In this case class correctness requires that the default initializations
ensure the invariant.




-- 
-- Bertrand Meyer
bertrand@eiffel.com