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From: bertrand@eiffel.UUCP (Bertrand Meyer)
Newsgroups: comp.lang.eiffel,comp.object
Subject: Re: Inheritance and Information Hiding
Message-ID: <496@eiffel.UUCP>
Date: 6 Feb 91 18:27:03 GMT
References: <488@eiffel.UUCP> <27A86309.281A@tct.uucp> <1991Feb5.130359.9735@bellcore.bellcore.com>
Organization: Interactive Software Engineering, Santa Barbara CA
Lines: 28

From <1991Feb5.130359.9735@bellcore.bellcore.com>
by caseau@maya.bellcore.com (Yves J Caseau):

> 2. My solution to the POLYGON/RECTANGLE problem.
> 
>    I tend to be simple minded:
>       a. a RECTANGLE is a POLYGON (thefore there must be inheritance)
>       b. Adding a vertex to a polygon produces ANOTHER polygon (a different
>          mathematical object)
>       c. Thus, rectangle inherit the property add_vertex, which produces
>          a pentagone from a rectangle
> 
>    Don't flame me on this, I know this is cheating ... but it makes a lot of
>    sense.


If one transposes the problem to applicative (rather than imperative)
programming, where there are no procedures but only functions
which do not produce side-effects, and also removes reference
assignment (which introduces aliasing), this solution indeed
works. Mirandeiffel?




-- 
-- Bertrand Meyer
bertrand@eiffel.com