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From: ell@access.digex.net (Ell)
Subject: Re: Module size (was Re: Software landmines)
Date: 1998/09/05
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Date: 1998-09-05T00:00:00+00:00
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"Pat Rogers" <progers@acm.org> wrote:

>Robert Martin wrote in message <6spfvf$nun$1@hirame.wwa.com>...
>>
>>As you know, in OO we create classes.  Classes declare methods (functions).

>Bruce Douglass says in his book "Real-Time UML"
>
>    A class can be thought of as the type of an object.
>
>The part I like is the footnote that accompanies the above sentence:
>
>    Strictly speaking, the type refers to the interface
>    of the object -- objects with the same interface
>    are of the same type, regardless of their class.
>    The class of an object defines its internal
>    implementation. This is not normally a useful
>    distinction unless you are using languages that
>    make the difference visible, such as Java.
>
>I think OO is about creating types, not classes.
>
>Just my $0.02.

Unfortunately in C++ even if the interface of 2 classes is the same
they are not polymorphically substitutable for each other unless they
both inherit from a common class.

Elliott