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From: bertrand@eiffel.UUCP (Bertrand Meyer)
Newsgroups: comp.object,comp.lang.eiffel
Subject: Re: Should a constructor do "work"?
Summary: Avoid creating inconsistent objects
Message-ID: <364@eiffel.UUCP>
Date: 12 Jul 90 19:23:03 GMT
References: <55236@microsoft.UUCP> <MOSS.90Jun15090015@ibis.cs.umass.edu> <519@tetrauk.UUCP>
Organization: Interactive Software Engineering, Santa Barbara CA
Lines: 19

From <519@tetrauk.UUCP> by rick@tetrauk.UUCP (Rick Jones):

> How should
> the language or the program design cope with a situation where an object is created, but
> its create routine ("constructor") is unable to satisfy the invariant due to some
> run-time condition which the program must trap in a non-fatal way.  In Eiffel an
> exception could be raised, and caught somewhere else, but that would not in itself
> prevent the existence of the invalid object.

	If invariants are checked and a creation operation raises
an exception, the target of the Create should remain void,
excluding any creation of an inconsistent object.


	This should definitely be part of the language
specification.
-- 
-- Bertrand Meyer
bertrand@eiffel.com