Re: Deallocating Task objects

["Norman H. Cohen" <ncohen@watson.ibm.com>]

Robert Dewar wrote:

> Much later, the ARG visited this issue, and declared that this situation
> was pathological, which meant that no compiler was expected to implement
> it (I do not remember if it was formally declared erroneous or not, I
> don't have my AI's with me right now). This meant that the test was
> challengable, but in fact, to my memory it did not get challenged, since
> this was late in the Ada 83 cycle.

It was not declared erroneous in Ada 83.  The ARG defined a new AI
category, "pathological", which said that the question at hand had
nothing to do with anything that could ever be useful in a real program,
and that even if the language gave a definite answer to the question, it
was not useful to write an ACVC test that would force implementors to
degrade their code to conform to that answer.  The later AI simply
reclassified the earlier AI from "binding interpretation" to
"pathological", meaning "Yes, a terminated task can be returned outside
of its master, but it's utterly useless to write a program that does
this, so we don't care if it works right, and we don't want implementors
degrading their implementations to make it work right."

However, as Robert notes, the implementors had already gone through all
the work of degrading their implementations, so the damage was done.

> Finally, it was fixed, in a rather nice and general way in Ada 95.

Yes, it falls out naturally as a consequence of more general rules about
"return by reference".

> Anyone want to add to or amend this bit of history (trying to remember
> things from this far back in detail is always a bit unreliable :-)

This time Robert's memory and mine are in accord.  :-)

-- 
Norman H. Cohen
mailto:ncohen@watson.ibm.com
http://www.research.ibm.com/people/n/ncohen