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

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 11 Sie, 17:30, John McCabe <j...@nospam.assen.demon.co.uk> wrote:

> I was just wondering if anyone here has been following the C++0x
> development, particularly wrt concurrency etc.

Yes.

> Obviously we all know that one of the big issues Ada compilers had in
> the early days was providing a supporting run-time system that was
> robust, efficient and reliable.

Right, we will come back to this statement.

> To be honest, I haven't been following the C++0x development but,
> based on what I have read about C++0x's threads stuff (based on
> Boost.Thread) am I right in assuming that all that's being proposed is
> a standardised abstraction of the threading functions of whatever OS
> that your C++ program is running on?

Yes. This basically standardizes the existing practice (which is very
good for users) and allows easier implementation (which is very good
for users).

> I'm fairly sure this is how many Ada implementations work anyway, but
> I believe there are (or have been) many Ada implementations developed
> for bare machines where the Ada vendor provided the run time system.

And there is absolutely nothing that could prevent the C++ vendor from
implementing a stand-alone run-time that will implement the given API.

> So, are we seeing something arriving in C++ that need only be
> supported by implementations running on a 3rd party OS

Absolutely not, see above. There is nothing that prevents vendors from
implementing stand-alone run-times. Actually, with the API that is
borrowed from *existing implementations* (read: maturity, industrial
experience, etc.), implementing such a stand-alone run-time is
actually much easier than being forced to work with API that is
constructed in isolation from the existing practise.
You might even pick a source code from the Linux kernel and build on
that. Why not? This is the comfort that Ada vendors did not have.

> or will threads need to be supported for bare machines
> as well?

No standard can force anybody to provide implementations. Vendors will
do it if they will see a business opportunity in it.

> Thanks for any responses.

You are welcome.

> This may seem like a C++ question, but it's
> more a question of "why will Ada's threading model remain vastly
> superior"!

Why do you think it is "vastly superior"? It is certainly more
complex, but the most visible effect of complexity is the cost (both
in time and money) of implementation and this is where we come back to
what you have stated at the beginning - the complexity of run-time has
*hurt* Ada heavily at the beginning and the consequences of it are
still visible in low adoption of the language.

Being complex does not guarantee higher expressiveness, either.

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com

Database Access Library for Ada: www.inspirel.com/soci-ada