Re: Private or public task ?

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

On 5 Lut, 22:53, Hibou57 (Yannick Duchêne) <yannick_duch...@yahoo.fr>
wrote:

> I did not ever suspected such a requirement. Transitive blocking is
> not allowed ?

As far as I understand, there is a careful wording around this subject
so that formally speaking protected operations (except for entries)
are not themselves "blocking". So, for example, you can call protected
operations from other protected operations.

The operations that are considered to be blocking in this context are
delay statements, entry calls, select statements and... I/O
operations. These cannot be called from protected operations.

(I'm sure somebody will correct me if I'm off tracks)

> So, if blocking operation are not allowed from a protected type,
> clients of a given operation have to know it weither or not it's
> potentially blocking,

That would be nice, yes. But be careful, this approach might blow up
the language. What about exception specifications? And so on.

But: see RavenSPARK.

The problem with blocking in particular is that there is no way to
verify whether imported subprograms (from C libraries, for example)
are blocking. You can import I/O operations from C libraries and there
is no way to verify what they do.

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

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