Re: [boost] Re: recommend logging library?

From: John Torjo (john.lists_at_[hidden])
Date: 2004-03-19 00:32:25

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

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() << ...;

Best,
John