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From: jhd@herold.franken.de (Joachim Durchholz)
Subject: Re: Real OO
Date: 1996/05/09
Message-ID: <68XCYN-k3RB@herold.franken.de>#1/1
X-Deja-AN: 154160567
references: <68P8IzIk3RB@herold.franken.de> <Dr4qpz.FMx@assip.csasyd.oz>
newsgroups: comp.lang.eiffel,comp.lang.ada,comp.object
Date: 1996-05-09T00:00:00+00:00
List-Id: <comp.lang.ada>


donh@syd.csa.com.au wrote 09.05.96 on Re: Real OO:

> :Well, Eiffel doesn't allow you to freeze parameter classes, so we have
> :a point where Ada allows a bit more freedom.
>
> Disagree. The fact that Eiffel allows you to redefine them to conformant
> types in descendants indicates greater freedom not less. There is no need to
> preclude redefinition and it is more flexible to be able to.

Depends on point of view. In Ada, I have more freedom in that I can  
specify more restrictions <g>...

More generally speaking, just because there is more freedom for  
programmers to use a routine, this automatically means the author of  
the routine is forced to be less restrictive about his parameters.

Of course, this is not a problem in Eiffel - the universally accepted  
rule is "wherever a class is named, a descendant will do" (with some  
notable exceptions, but these are intended for special cases and not  
for normal use).

Still, I don't have a good Eiffel variant of the  
corresponding_parts_equal routine earlier in this thread. Any takers?


-Joachim

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