Re: Timeouts in Ada

["Randy Brukardt" <randy@rrsoftware.com>]

"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message 
news:wccppgu9398.fsf@shell01.TheWorld.com...
...
> I think the reason multiple entries are not allowed is that during the
> Ada 9X project, it was thought to be too hard to implement.
> Or too hard to implement on existing implementations (which of course
> had not been designed for that).

It wasn't so much that it was too hard to implement, but that it was too 
hard to implement better than a programmer could write themselves. I recall 
something about essentially having to poll the entries. I don't know 
off-hand if there would have been some way to implement it sensibly if one 
was starting from scratch; I do remember that none of the 3 teams that 
analyzed the feature could come up with an efficient implementation. The 
real problem was that the people that were requesting the feature were 
hard-real time types that expect everything to happen immediately -- and 
that's not how this was going to work in practice.

We also analyzed ATC, which is equally expensive. But of course that did get 
in, because the expensive implementation is OK for the sorts of uses that it 
puts too.

It would be interesting to find those papers; I'm sure I still have them in 
a dusty box somewhere. (Our paper should also be on-line somewhere here, but 
it's not on my current computer, so finding it would be interesting.)

                             Randy.