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Date: Tue, 30 Jul 2002 18:10:18 -0400
From: Hyman Rosen <hyrosen@mail.com>
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Subject: Re: Multiple interface inheritance workaround in Ada 95 / Ada 0x
 to satisfy a Java language advocate?
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Date: 2002-07-30T18:10:18-04:00
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Robert A Duff wrote:
> I would like to see an example of why it is wanted.  On the face of it,
> it seems weird to reach off into the far distance and ask whether this
> thing I have my hands on just *happens* to obey some totally unrelated
> interface.

In C++, it's just a part of RTTI (run-time type inquiry).

I imagine it's used mostly in "interface discovery" contexts.
That is, you have a pointer to an interface, and you want to
know whether the underlying object supports other, possibly
related interfaces. So you do the cast, and if returns a
non-null value, you know the interface is supported. Both
COM and CORBA have very similar concepts.