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From: Jeff Carter <spam.carter.not@spam.innocon.com>
Subject: Re: Wanted: Ada STL.  Reward: Ada's Future
Date: 1999/02/01
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Date: 1999-02-01T00:00:00+00:00
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Matthew Heaney and Alexy V Khrabrov have been arguing about the need for
sets. Heaney never uses them and Khrabrov considers them essential.

I've recently used sets for a communications protocol. The task needs to
wait for one of a set of events; at other times it needs to wait for one
of another set of events. The sets of events overlap.

This mapped nicely to a protected object with a current event component.
Each Wait_ entry has a barrier of the form

when Member (Current_Event, Set_Of_Events_For_This_Kind_Of_Wait) is

Another task calls a Signal entry to set Current_Event. This worked very
well.

These are small, simple, discrete sets, as in Pascal, implemented as
arrays of Boolean, as opposed to the set-of-anything components I often
see discussed. I've never needed a set of anything except discrete
values, but I have needed bags of anything.
-- 
Jeff Carter
E-mail: carter commercial-at innocon [period | full stop] com
"We call your door-opening request a silly thing."
Monty Python & the Holy Grail