Re: Ada 95 tasking problems with Ada 83 code

[Richard Riehle <laoXhai@ix.netcom.com>]

Jeff Creem wrote:

> "Wayne Lydecker" <wayne@mtws.visicom.com> wrote in message
> news:39B046AE.A05C82AA@mtws.visicom.com...
>
> Stuff Deleted
> > launched the software-to-debug via a task.  The first get_line locks it
> > up solid.  I find it hard believe that a get_line blocks all tasks in ada
> 95
> > but not in ada 83, and they provide no simple alternative.  I guess I have
> > to write my own get_line that uses get_immediate, which does not block the
> > tasks from running.  I wish to thank everyone for all of their wonderful
> > comments.  I have successfully proven that our code can be ported to a
> > PC running Linux.
> >
> > -- Wayne.
>
> Actually this is not a difference between Ada 83 and Ada 95 but a difference
> between implementations. There are many implementations of Ada 95 on
> which Get_Line does not block the entire process. There are also plenty of
> Ada 83 environments in which Get_Line (or more often in both cases other
> blocking OS calls) blocks the entire process.
>
> It may be allowed by the RM but I would find such an environment too
> restrictive
> and would not use it for any "real" work. (Ok I can hear the gates opening
> from
> people who will compain that to write such a program is erroneous or
> something.)

Jeff,

Your message,  much of which I snipped in this reply, was informative and had an

excellent collection of ideas related to the various operating systems
involved.  I
will save it for my own collection of reminders of stuff to look at when doing
design.

My only concern about the information is that of design for portability.   You
anticipated,
to some extent, that concern by referring the notion of an "erroneous"
program.   Of
course, each environment is different and that is why we cannot really deploy
software
without understanding the vagaries of each platform.   On the other hand,  if  I
do know
that a particular construct may have a blocking protocol on one platform and not
on
another, would it not be wise of me to select the alternative most likely to
give me
a working solution regardless of the underlying operating system protocol?
Granted,
this is not always possible and may sometimes accrue greater overhead.   Perhaps
it
is an overly cautious approach, but then I am also a defensive driver who takes
twice
as long to reach my destination as anyone else (probably a function of my
Old-Order
Amish ancestry).

Richard Riehle
laoxhai@ix.netcom.com