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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: C++0x : no 'concepts'
Newsgroups: comp.lang.ada
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Date: Wed, 9 Sep 2009 14:39:44 +0200
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Date: 2009-09-09T14:39:44+02:00
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On Wed, 09 Sep 2009 14:12:21 +0200, Georg Bauhaus wrote:

> Martin schrieb:
>> Crickey! How glad am Ada has strong typing and a generic contract
>> model!!
>> 
>> http://www.ddj.com/cpp/218600111
>> 
>> And that was going to make life 'simpler'!?!?!?
> 
> Just saw this, addressing the question:
> 
> "The current definition of concepts and requirements for use drowns the
> programmer in complexities of a magnitude not warranted by the need to
> express type-checked 9constrained) generic programming."
> 
> From: Simplifying the use of concepts, linked in the article.
> 
> -
> 
> Fantasizing, could we have, in Ada,
> 
> - recursive instantiations of pure generics?

Huh, the second edition of interfaces, now for the "Ada preprocessor"? I
read you that all instances of the same body when instantiated
automatically will be considered "same". Right?

> - an optional Compiler package?

The idea of Ada generics is that types aren't checked beyond a handful of
built-in classes like "<>", "private", "limited private" etc and operations
specified explicitly as formal parameters. This is not a contract of a type
or a set of types, that can be dealt with, e.g. constrained, extended, at
least named.

If you had truly "type-checked  & constrained" formal generic parameter,
you would not need to handle it as a subject of wild substitutions in the
generic unit. You would probably be able to use it as-is, without
instantiation...

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de