Boost logo

Boost :

From: Daniel Frey (daniel.frey_at_[hidden])
Date: 2004-03-19 03:07:45

John Torjo wrote:
>> I think it's the wrong approach. In our company we have implemented
>> logging through macros which has one very important property: When I
>> write
>> LOG_DEBUG( whatever() );
>> into my source, then whatever() is only evaluated when the
>> debug-logger is active. The macro basically expands to something like
>> this:
>> if( Base::hasLogger( LogLevel::DEBUG ) )
>> Base::log( whatever(), LogLevel::DEBUG );
>> I think this cannot be done without macros as normal function calls
>> (including operator<< for streams) need to evaluate their arguments
>> before they are called. As the difference in the application execution
>> speed can vary by a factor of 1000, this is a very valuable
>> optimization for us. My 2¢.
> Man, you must be doing a LOT of logging ;)

Well, too much for my taste, but some other team-members (namely by boss
:) insists on logging almost everything. And I have to admit that it can
be a real help from time-to-time. I just wish I would be allowed to
implement a better hasLogger() so I can selectively enable only the
log-messages/areas/levels/... that I'm interested in :)

> I do quite a lot of logging myself, but I've never needed anything like
> above.

Maybe because when the framework doesn't support the feature I mentioned
above, you won't add anything that makes the programm 1000x slower to
your logging? ;)

> Anyway, in my code I have functions, which return a log_stream (a
> thread-safe wrapper over a stream).
> And use it like this:
> activity_log() << "My app. started at" << time(0) << std::endl;
> error_log() << "should have not arrived here" << std::endl;
> // etc.
> And if I truly want, I can implement an operator bool(), and be able to
> disable it at runtime, like this:
> if (activity_log()) activity_log() << ...;

Hm, too verbose for my taste. With the macro, you get it for free.

Regards, Daniel

Daniel Frey
aixigo AG - financial solutions & technology
Schloß-Rahe-Straße 15, 52072 Aachen, Germany
fon: +49 (0)241 936737-42, fax: +49 (0)241 936737-99
eMail: daniel.frey_at_[hidden], web:

Boost list run by bdawes at, gregod at, cpdaniel at, john at