Re: [boost] Re: recommend logging library?

From: John Torjo (john.lists_at_[hidden])
Date: 2004-03-19 05:28:32

Daniel Frey wrote:

> 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.
>
True. I can also add a macro, something like:

log(activity) << ...;

Best,
John