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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: GOTO considered necessary (reworked)
Date: 1997/06/21
Message-ID: <EC3u70.Ksu@world.std.com>#1/1
X-Deja-AN: 251478857
References: <5nn2fm$11dk$1@prime.imagin.net> <dewar.866539123@merv>
 <EBxpxC.417@world.std.com> <dewar.866851059@merv>
Organization: The World Public Access UNIX, Brookline, MA
Newsgroups: comp.lang.ada
Date: 1997-06-21T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <dewar.866851059@merv>, Robert Dewar <dewar@merv.cs.nyu.edu> wrote:
>Robert Duff says
>
><<I object to the term "fundamental" above.  I believe it is possible
>(though not easy) to implement controlled types with near-zero overhead
>on entering and leaving the scope of a controlled variable.>>
>
>First, you certainly can't eliminate the actual initializatoin and
>finalization (unless you are *very* clever indeed :-)

Of course.  That's not "overhead".  That's what the program want's to
do, and of course that code needs to get executed, in general.

>Second, eliminating the overhead from abort deferral if you are on top
>of an operating system is extremely complex.

Granted.  However, a program without aborts (or, without any tasking at
all) doesn't need that overhead.  That's what pragma Restrictions is
for.  I didn't say it's "easy" to eliminate this overhead -- I said it's
possible.

But the overhead I was thinking of was the overhead of automatically
putting controlled objects onto lists and taking them off, which is also
possible, but not easy, to eliminate.

- Bob