Re: [Boost-users] yet another logging library

From: Nat Goodspeed (nat_at_[hidden])
Date: 2008-06-12 10:23:28

Mojmir Svoboda wrote:

>>   The user should be able to specify that at runtime - what if he wants 
>> to configure the log at runtime?
> 
> no he will _NOT_, that is the beauty ;)) if he still do, let him use log4jpp.
> according to my (i admit that short perhaps) experiences, this is very
> rarely needed.
> you can either modify source and recompile or use log4j++ like i said.

My experience is with large products with many subsystems, worked on by 
many developers over the course of years.

The most effective logging machinery:

- Allows you to turn on logging at runtime, so your support person in 
e-mail dialog with an irritated user can say, "Okay, please set this 
configuration switch and try that again." Some bugs can only be 
reproduced on a user's machine. On the other hand, you don't want to 
generate large log files for every user, every run.

- Allows you to be selective about what logging output is produced, 
because if you turn on EVERYTHING, your user has trouble even storing 
and mailing you the resulting file -- never mind your problems trying to 
discover what might be relevant. (This is the result of accumulating 
helpful logging output in many interacting subsystems over the course of 
years.)

- Has trivial runtime cost for a suppressed log message. In particular, 
no string allocation or formatting is performed. Ideally, the amortized 
runtime cost is nothing more than examining a static bool and a jump.

There are probably people for whom compile-time controls suffice. But 
such a library wouldn't be useful to our developers.