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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: why learn C?
Newsgroups: comp.lang.ada
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Date: Mon, 2 Apr 2007 14:04:18 +0200
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Date: 2007-04-02T14:04:18+02:00
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On 2 Apr 2007 01:19:19 -0700, kevin  cline wrote:

> On Apr 2, 2:52 am, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
> wrote:
> 
>> 1. Here you compare the language of templates (a quite crippled one) with
>> the language in which the Ada compiler was written.
> 
> Probably C or C++.

Ask AdaCore.

As for me, I have developed compilers of specialized languages in C++, Ada,
even in Assembly (with macros). No, I wouldn't advise anybody to use C++
for compiler construction...

>> Clearly, this
>> comparison cannot be in favor of templates. In case you doubt it, try write
>> a parser and code generator in C++ templates...
> 
> The Ada compiler is closed.  I can't go modify the Ada compiler and
> get it to ensure that the physical units in my Ada program are
> consistent.

You don't need to modify the compiler for that.

If you meant static checks, then it were trivially impossible in general
case. Units can be statically checked only under certain [rather rare]
conditions.

A good design should support static checks where possible and go run-time
elsewhere. Templated / generic solution obviously does not scale.

>  But I can use C++ templates to define a type algebra,

Which is a wrong way in a statically typed language, because see above.

It should be an algebra of the type *constraints*, which C++ has no notion
of.

> and
> then use those types to insure that the equations in my C++ program
> are consistent.

Try �C, K, sqrt (m�), then come back.

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