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From: LeakyStain <leakstan@erols.com>
Subject: Re: Stream venting (long)
Date: 1998/12/31
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NNTP-Posting-Date: 31 Dec 1998 12:27:08 GMT
Newsgroups: comp.lang.ada
Date: 1998-12-31T12:27:08+00:00
List-Id: <comp.lang.ada>

robert_dewar@my-dejanews.com wrote:
> 
> Of *course* the locking belongs in the attribute routines,
> it could not be anywhere else. As for crappy interface, it
> is perfectly trivial to make an interface that simply
> allows:
> 
>    Stream_Lock;
>    ...
>    Stream_Unlock;
> 
> to be placed in each attribute routine for which atomicity
> is required (these primitives would properly take care of
> nesting).
> 
> (a) what is so crappy about this interface?

You could implement a lock using a Controlled type, where Initialize
locks and Finalize unlocks, giving this usage:

    declare
	Stream_Locker;
    begin
	stream use
    end;

That way, you don't have to worry about unlocking on exceptions. I
suspect Ted Dennison still won't be happy.

> (b) how could it possibly be avoided

No way, as you say, this is where it needs to be.

-- Stephe