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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Disabling string evaluation in a logging system
Newsgroups: comp.lang.ada
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Date: Tue, 18 May 2010 10:15:48 +0200
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Date: 2010-05-18T10:15:48+02:00
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On Tue, 18 May 2010 00:48:38 -0700 (PDT), dhenry wrote:

> I'd like to avoid the string evaluation if the logging is disabled
> (because it consumes CPU resources).
> 
> A possible solution would be to test the log level before the
> procedure call:
> 
> if Log_Level > 0 then
>   Log.Write ("Parameter " & To_String (Param_Name) & " Value = " &
> Integer'Image (X), Log_Level);
> end if;

I am using this way, but rather as:

if Log.Level in Warning..Severe then
   Log.Write (...);
end if;

> But with thousands of logging lines everywhere in my application, it
> will make the code quite unreadable and introduces a lot of if-test
> pollution (and it's really boring to write).

I don't see much more pollution than a call to Log.Write has already
inflicted.

> I'm wondering how in Ada 95 and/or Ada 2005 I could write such a
> logging system (if it's possible). The goal is that logging should not
> be too intrusive in my code.

AFAIK, there is no way.

But if I were to make a proposal, then I would do the useless pargma Assert
useful. E.g.

   pragma Assert (Condition, Message);

[Change]
Dynamic semantics: Message is evaluated only if Condition is evaluated to
true. Then a user-defined assertion handler is called, if any (to be set by
Assertion_Policy). Otherwise Assertion_Error is propagated.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de