Re: C++0x and Threads - a poor relation to Ada's tasking model?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Thu, 13 Aug 2009 13:32:18 +0200, Pascal Obry wrote:

>> Don't you wonder why should it be this way? Shouldn't safer code be more
>> efficient?
> 
> Should... maybe! My experiences is often that Ada is a *bit* slower. I 
> have also some experiences where a concurrent and distributed 
> application in Ada was a bit faster than a C++ one using OpenMP + MPI.

In that case there must be something suboptimal in the language design.

I would also argue that where C++ is faster, the corresponding C++ code is
probably wrong, which a full coverage test would show. The trick is, that
nobody tests the code.

>> properly defined allows a deeper optimization and safer programming.
> 
> Well checks are still taking some time. Note that I was speaking of 
> applications built with checks on.

To continue the argument above:

1. These checks must be there, else the program is wrong
2. The language is wrong not allowing programmer to design these checks
static [*]

When it is neither 1 nor 2, then it is something which we can prove to be
OK in our program, while the compiler cannot. Is a normal programmer that
smart?

-----------
* Example in Ada. If you wanted to iterate two arrays at once, you could
not eliminate index checks of one of them:

   for I in A'Range loop
      ... A (I) + B (I + B'First - A'First) ...
                             -- No way to eliminate B index check
   end loop;

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