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From: d87-mra@dront.nada.kth.se (Magnus Ramstr|m)
Newsgroups: comp.object
Subject: Re: Do we really need types in OOPL's?
Message-ID: <1990Sep22.105455.14445@kth.se>
Date: 22 Sep 90 10:54:55 GMT
References: <0yw10qr@Unify.Com> <275@sps.com> <698@servio.UUCP>
Organization: Royal Institute of Technology, Stockholm, Sweden
Lines: 15

In article <698@servio.UUCP> riks@servio.UUCP (Rik Fischer Smoody) writes:
>
>Furthermore (not my recommendation, just an observation),an inheritance system
>typically allows a user defined subclass to BREAK the (unmanaged) protocol
>of a superclass.  E.g. if I created Bucket,subclass of Container,but overwrote
>#do: such that it is not compatible with the normal expectation of #do:, then
>even though a type-checking system would allow a Bucket, it would NOT work.
>
Everywhere where a Bucket would be allowed as a Container, it would be a
Container. Virtual messages only would kick off differing methods, but
that is the idea. I too do not recommend breaking methods of superclasses,
but being able to add to them or implementing the same thing somewhat 
differently is very useful.
/mr
d87-mra@nada.kth.se (Magnus Ramstr|m). Student @ Dep. of Computer Science.