From: Robert A Duff <bobduff@shell01.TheWorld.com>
Subject: Re: This can't be done in Ada...or?
Date: 11 Feb 2005 13:27:11 -0500
Date: 2005-02-11T13:27:11-05:00 [thread overview]
Message-ID: <wcck6pf54w0.fsf@shell01.TheWorld.com> (raw)
In-Reply-To: xtadnQ1DlL2teJHfRVn-qw@comcast.com
Jeff C <jcreem@yahoo.com> writes:
> Per Lindquist wrote:
> > 3. does *not* cause any execution overhead if disabled.
...
> > I say it can't be done in Ada. Please prove me wrong!
> 3) Pragma Inline the procedure calls. Put the "if Logging_Enabled"
> inside the logging procedures. Make the Logging_Enabled a static
> constant. Compiler should optimize away the entire procedure call if
> done properly (it does on GNAT and VADS for the cases I have tried)
The compiler can optimize away everything inside the "if
Logging_Enabled". But it can't optimize away the evaluation of the
parameters unless it can prove the absence of side effects.
For example:
Trace.Error(..., "Bad value of X " & Debug_Info(X));
where Debug_Info is some user-defined function that produces useful
debug info about some complicated data structure called X.
It has no side effects, but the compiler doesn't know that, usually.
I suppose you could always write Debug_Info like this:
function Debug_Info(...) return String;
pragma Inline(Debug_Info);
-- Don't call this unless Logging_Enabled is True!
function Debug_Info(...) return String is
begin
if Logging_Enabled then
return The_Real_Debug_Info(...);
else
raise Program_Error;
end if;
end Debug_Info;
But then you have to write two versions of Debug_Info
for every type. So I'd say the original poster's statement,
"it can't be done in Ada" is pretty true, if zero run-time overhead
is required.
In my code, I usually do as you suggested, but *also* add "if
Logging_Enabled" or whatever around calls if the parameter evaluation
could be expensive. This provides *almost* what the original poster
asked for -- you need the annoying "if Logging_Enabled" only sometimes.
- Bob
next prev parent reply other threads:[~2005-02-11 18:27 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-11 16:33 This can't be done in Ada...or? Per Lindquist
2005-02-11 16:51 ` Duncan Sands
2005-02-12 19:55 ` Florian Weimer
2005-02-14 8:34 ` Per Lindquist
2005-02-14 8:17 ` Per Lindquist
2005-02-11 17:02 ` Jeff C
2005-02-11 18:27 ` Robert A Duff [this message]
2005-02-11 23:51 ` Ludovic Brenta
2005-02-11 23:52 ` Robert A Duff
2005-02-12 13:55 ` Duncan Sands
2005-02-12 14:58 ` Martin Krischik
2005-02-12 15:56 ` Martin Dowie
2005-02-12 19:02 ` Robert A Duff
2005-02-14 8:49 ` Per Lindquist
2005-02-11 17:08 ` Jerome Hugues
2005-02-14 9:05 ` Per Lindquist
2005-02-14 13:07 ` Georg Bauhaus
2005-02-12 1:10 ` Jeffrey Carter
2005-02-12 14:01 ` Duncan Sands
2005-02-13 0:27 ` Jeffrey Carter
2005-02-14 9:10 ` Per Lindquist
2005-02-15 0:40 ` Jeffrey Carter
2005-02-15 7:40 ` Per Lindquist
2005-02-15 8:39 ` OT: Google reply (Was: Re: This can't be done in Ada...or?) Adrien Plisson
2005-02-15 9:42 ` Per Lindquist
2005-02-15 8:27 ` This can't be done in Ada...or? Per Lindquist
2005-02-14 22:10 ` Manuel G. R.
2005-02-15 8:47 ` Mark Lorenzen
2005-02-15 9:09 ` Jacob Sparre Andersen
2005-02-15 9:31 ` Mark Lorenzen
2005-02-15 9:48 ` Jacob Sparre Andersen
2005-02-15 10:07 ` Mark Lorenzen
2005-02-15 10:15 ` Martin Dowie
2005-02-17 22:09 ` Randy Brukardt
2005-02-18 6:53 ` Martin Dowie
2005-02-15 13:46 ` Robert A Duff
2005-02-15 13:41 ` Robert A Duff
2005-02-15 16:30 ` Per Lindquist
2005-02-15 19:38 ` Martin Dowie
2005-02-15 20:20 ` Robert A Duff
2005-02-17 21:52 ` Simon Wright
2005-02-17 22:06 ` Randy Brukardt
2005-02-17 22:40 ` Mark Lorenzen
2005-02-16 0:04 ` Jeffrey Carter
2005-02-16 0:09 ` Jeffrey Carter
2005-02-17 9:47 ` Per Lindquist
2005-02-17 22:36 ` Randy Brukardt
2005-02-14 15:21 ` Peter Amey
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