Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!mcsun!hp4nl!star.cs.vu.nl!jos
From: jos@cs.vu.nl (Jos Warmer)
Newsgroups: comp.lang.eiffel
Subject: Re: Problems with non-conforming Create?!
Keywords: eiffel, redefinition, create, conformance
Message-ID: <5283@star.cs.vu.nl>
Date: 5 Feb 90 10:31:18 GMT
References: <1990Jan30.132802.15815@isy.liu.se>
Sender: news@cs.vu.nl
Distribution: comp
Organization: Fac. Wiskunde & Informatica, VU, Amsterdam
Lines: 28

In article <1990Jan30.132802.15815@isy.liu.se> nicwi@isy.liu.se ( Niclas Wiberg) writes:
>I think I have discovered a problem concerning the Create routine.
>Perhaps this would have been fixed in the coming release, but still
>I believe it is worth mentioning:
>
>The problem arises because you are allowed to redefine the Create
>routine (in a descendant class) with no concern of conformance
>rules. Consider the classes PARENT and CHILD:

You are right, this a a known `hole' in the eiffel type system.
It happens also with other routines than Create.

>As far as I can see, there is nothing illegal in the example
>above, although it is very "constructed". Or am I wrong?

I have not seen the solution yet, although one will have to come
This example might look very constructed, but I ran into it
during normal program development.  So it gives real problems.



                                 Jos Warmer
				 jos@cs.vu.nl
				 ...uunet!mcvax!cs.vu.nl!jos
--
                                 Jos Warmer
				 jos@cs.vu.nl
				 ...uunet!mcvax!cs.vu.nl!jos