Logging in Clojure

Question

For Java development, I use Slf4j and Logback.

Logger logger = LoggerFactory.getLogger(HelloWorld.class);
logger.debug("Hello world.");

How to use these two libs in Clojure programs? Majority of Clojure programming doesn't has .class concept (possible of course via AOT).

What do you use for logging in Clojure?

There are two overloads for `getLog()`: one uses a `Class`, the other takes a `String`. You could simply use the `String` one. — Joachim Sauer, Mar 07 '11 at 12:56

score 36 · Accepted Answer · edited Nov 10 '12 at 09:28

36

Clojure comes with a logging core library in tools.logging. Add [org.clojure/tools.logging "0.2.3"] to your leiningen project.clj and run $lein deps as usual.

Once you use the library you can start logging away

(use 'clojure.tools.logging)
(warn "something bad happened")

Now you can also access the logger object and set the required fields, refer to the following article for this (written for the older contrib-lib but the same ideas apply):

http://www.paullegato.com/blog/setting-clojure-log-level/

edited Nov 10 '12 at 09:28

claj

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answered Mar 07 '11 at 13:11

pyr

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10

contrib is deprecated in favor of tools.logging https://github.com/clojure/tools.logging – Sridhar Ratnakumar Oct 17 '11 at 19:46

score 13 · Answer 2 · answered Apr 09 '13 at 13:58

13

Look at this as well https://github.com/ptaoussanis/timbre . It looks very simple and nicely done.

answered Apr 09 '13 at 13:58

joshua

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Actually timbre is what I prefer as out of the box logging! spy and other functionality is very helpful. – claj Oct 23 '14 at 20:04
2

Here is another question that covers Timbre logging in more detail: http://stackoverflow.com/questions/32310619/clojure-configure-timbre-logging/32340732#32340732 – Alan Thompson Sep 02 '15 at 17:47

score 9 · Answer 3 · answered Oct 12 '11 at 15:18

9

tools.logging. For details, refer to tools.logging vs clojure.contrib.logging

answered Oct 12 '11 at 15:18

Jingguo Yao

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score 5 · Answer 4 · answered Mar 07 '11 at 19:42

some excerpts from a one of my projects that uses log4j:

log.clj:

(ns 
    #^{:author "Arthur Ulfeldt", 
       :doc "Polynomial threshold encryption"}
  com.cryptovide.log
  (:gen-class)
  (:use
   clojure.contrib.logging))

...

(def logger (org.apache.log4j.Logger/getLogger "A1"))
(def log-levels (vec ( org.apache.log4j.Level/getAllPossiblePriorities)))

...

(defn start-logging []
  (org.apache.log4j.BasicConfigurator/configure))

main.clj:

(start-logging)
(. logger setLevel (log-levels verbose-level))

Logging in Clojure

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