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From: stt@ada-uts
Newsgroups: comp.lang.ada
Subject: Re: a tasking question for you
Message-ID: <57900037@ada-uts>
Date: Tue, 14-Jul-87 13:45:00 EDT
Article-I.D.: ada-uts.57900037
Posted: Tue Jul 14 13:45:00 1987
Date-Received: Sat, 18-Jul-87 06:59:03 EDT
References: <13@<12317696882>
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Nf-From: ada-uts!stt    Jul 14 13:45:00 1987
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Although I agree it is not specific here, it would not
be meaningful for a rendezvous to continue after
the caller receives TASKING_ERROR and begins to process it.
A rendezvous by definition occupies the full attentions
of both tasks.  To be clear, it should probably say
that TASKING_ERROR is raised no sooner than the completion
of the rendezvous, and no later than the abnormal completion
of the aborted task.

As far as 9.10:8 -- Imagine a variable which is a large record
being updated by record assignment.  If a task is aborted
and becomes completed in the middle of the assignment,
then the value of the variable may be unmeaningful, with
the record only partially updated, and perhaps even a single
component only partially updated.  In this sense,
the value is formally "undefined," which means that it is erroneous
to use or rely on the value.  Similar wording appears
in 3.2.1:17/18, where it states that "The execution of
a program is erroneous if it attempts to evaluate a scalar
variable with an undefined value.  Similarly, the execution
of a program is erroneous if it attempts to apply a predefined
operator to a variable that has a scalar subcomponent with an
undefined value."

S. Tucker Taft
c/o Intermetrics, Inc.
Cambridge, MA  02138