"Matthew Heaney" <mheaney@on2.com> a �crit dans le message news: u41cg9jaqnrs56@corp.supernews.com...
>
> "Nick Roberts" <nickroberts@adaos.worldonline.co.uk> wrote in message
> news:a1o2h1$sfe3f$5@ID-25716.news.dfncis.de...
> > However, really, a much better design is like this:
>
> No, because protected operations can't make blocking calls.
>
> Note that all predefined I/O packages are "potentially blocking," which
> means, for example, that you can't call Text_IO from inside a protected
> object.
>
> So you still need a semaphore-style type (as in the original post), to
> handle the situation in which blocking calls are made inside a critical
> section.  The technique shown using a Limited_Controlled type to
> automatically seize and release the semaphore is a standard Ada95 idiom.
>
Have a look at package Protection from Adalog's components page (http://www.adalog.fr/compo2.htm) for a component that automates
this idiom.

--
---------------------------------------------------------
           J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr