[slf4j-dev] Category of Logger vs. name of containing class.

[Endre Stølsvik]

| But as I think you realize, it is not necessarily the best hierarchy for 
| production environments.

I've never used the classname.

If I could attach one Logger to "several names", so that if I do 
httpRedUserAuthLog.info("Red User ["+user.getName()+"] has 
authenticated."), the log statement would be injected both on the auth 
category ("Septim.AUTH.user" or whatever, "Septim" being my imaginary 
server), on the server-core category ("Septim.CORE.httphandler" or 
whatever), and on the color category ("Septim.Color.red"), then that might 
be a cool new feature without introducing much extra complexity.

 // Make Logger, with primary, mandatory category
 Logger httpUserRedAuthLog = Logger.getLogger("Septim.AUTH.user")
 // Additional categories
 httpUserRedAuthLog.addCategory("Septim.CORE.httphandler")
 httpUserRedAuthLog.addCategory("Septim.Color.red")

Logger.addCategory(String extraCat) would thus be the only new API-level 
method..

The first element here, that this log-statement would end up in three 
different files, is already solved in at least log4j by instead of 
injecting into three categories, one would inject to only the one 
category, and configuring that category to append to all three Appenders.
  But, with some clever log-configuration and the multiple category 
attachment feature above, I could ALSO state more specifically that I want 
only all "Colored Auth" statements to go to this particluar file.
  The example might be useless, but in any case, it would maybe solve some 
of the axes-problems? - You basically introduce a new axis by adding a new 
category to several loggers.

However, I realize that this solution has limitation that the Marker 
approach would fix: you cannot switch that easily between red and green 
users, w/o making a lot different colored loggers. So Marker is a nice 
idea, but what about not introducing a new concept, and instead just 
enabling method-specific injections of additional categories?

 // Make Logger, with primary, mandatory category
 Logger httpUserAuthLog = Logger.getLogger("Septim.AUTH.user")
 // Additional categories
 httpUserAuthLog.addCategory("Septim.CORE.httphandler")

 // log line
 httpUserAuthLog.info("Septim.Color.red", "User ["+user.getName()+"] has 
authenticated.");

.. basically the exact same idea as the current "Marker" approach, but 
that the markers are just additional categories? If there is a problem 
with the log method signatures, then by all means keep the Marker 
interface / simple class, but just as a wrapper around a String denoting 
the category.
  It would require versions with 'Marker marker' and 'Marker[] markers' to 
all the log methods - thus obviously multiplying the existing methods by 
three!


Regards,
Endre.