Hi Laurent, I believe using (log :fine (expensive-calc)) will do precisely what you describe (not do anything unless level :fine is enabled, and return nil)
(debug (some-expr)) is intended when you want to leave the logic precisely as is but display part of the calculation; (+ a b (- c d)) ; I can easily examine part of the equation that I think might be wrong: (+ a b (debug (- c d))) This produces the same output and logic as the original statement, but if the logging level is :fine then it will additionally log the intermediate part. I find both forms useful. Unfortunately the naming gives no clue as to the differences between them. Regards, Tim. On Jul 23, 7:27 pm, Laurent PETIT <laurent.pe...@gmail.com> wrote: > Hello, > > 2009/7/23 ataggart <alex.tagg...@gmail.com> > > > > > > > > > Ok, I've updated the code with some of Tim's code: > >http://paste.lisp.org/display/84053 > > > The "public" functions/macros are: > > > enabled? [level] [level log-name] > > true/false whether that level is enabled for the current namespace > > or log-name > > > log [level message ...] > > logs the message either directly or via an agent. The selection > > logic defaults to agent, unless the *allow-direct-logging* flag is set > > to true and the log is not being called from within a running > > transaction. > > > debug [expr] > > Evaluates and returns the expr. If debug is enabled logs the form > > and its result. > > One of the problems with logging in traditional java is that you have to > encapsulate your call to debug with an isDebugEnabled (for example) call > before doing a potentially heavy computation for expr : > > if (log.isDebugEnabled()) { > String message = <potentially heavy computation>; > log.debug(message); > > } > > In clojure, with macros, it is easy to get rid of this verbose pattern: > (debug <potentially heavy computation>) => the macro can generate the > boilerplate for us. > > But I see your debug function/macro always returns the result, so the > problem we had in java remains intact ? > What about just making debug return nil (so that it's clear that its primary > use implies a side effect) and generate the code to only evaluate the > expression generating the message if necessary ? > > I know that it would make you change a lot of your library, but I think this > functionality is important. > > Regards, > > -- > Laurent --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
