Re: Can any one shed some light on this problem.

["Jeff Creem" <jeff@thecreems.com>]

----- Original Message -----
>
> > > I have bean asked to examine the synchronization mechanism
> > > (rendez-vous) which is promoted by ADA and contrast this to the
> > > Dijkstra's (p/v) wait and signal mechanism.
> >
> > I'm afraid I can't say much on this, someone else might be able to help.
>
>     With a protected object you can *very easily* code a semaphore.
> Probably only of interest for educational purposes and toy programs.
>

Actually using a protected object to code a semaphore is also very useful
for creating portable semaphore packages to replace vendor specific
packages.

In Ada 83 it was somewhat common for people to use some sort of semaphore
package (either vendor specific or tied to the OS services) for signaling
and/or
mutual exclusion since the only built in language  feature for this was the
rendevous. I know of a
150K+ line of code Ada 83 project that was originally built for vxWorks with
a project
specific semi-thick binding on top of vxWorks semaphores that was ported to
run as
a simulation on an SGI (should work anywhere now) by replacing the body of
the semaphore
package with a protected object based implementation.