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From: dmitry@elros.cbb-automation.de (Dmitry A. Kazakov)
Newsgroups: comp.lang.ada
Subject: Re: ada vs. cpp
Date: Wed, 14 Nov 2001 09:29:33 GMT
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Date: 2001-11-14T09:29:33+00:00
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On Tue, 13 Nov 2001 16:05:41 GMT, Ted Dennison<dennison@telepath.com>
wrote:

>In article <3bf0e265.74480421@News.CIS.DFN.DE>, Dmitry A. Kazakov says...
>>template <int From, int To> class String {...};
>>
>>Here the string bounds identify the type. Which has a nasty
>>consequence that String<1,10> and String<1,80> are two different
>>types.
>
>It should be noted that this is a *theoretical* example Dmitry is presenting.
>C++'s "string" class is *not* defined this way. It is rather a single
>instantiation of another template, and thus all objects of this class *are* the
>same type.

Yes. It was just an example of strings with bounds as a part of the
type.

Another thing is that there is no other way (I believe) to do it if
stack allocation is a requirement.

>Another thing I noticed with C++ templates is that instantiations that use the
>same parameters appear to actually *be* the same object, unlike how Ada generics
>work. That actually would help alleviate this problem a bit more than if you had
>the same problem in Ada.

This is the problem of generics per se. They are inherently harmful. I
like to view dispatching polymorphism in OO as an attempt to get rid
of generics [and still have generic programming].

That C++ uses "by-value matching" solves nothing, though the errors it
may induce are very hard to track down. So I think Ada is in a better
position here.

Regards,
Dmitry Kazakov