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+;;; javalog.clj -- convenient access to java.util.logging in Clojure
+
+;; by Stuart Sierra <mail@stuartsierra.com>
+;; April 8, 2008
+
+;; Copyright (c) 2008 Stuart Sierra. All rights reserved.  The use and
+;; distribution terms for this software are covered by the Common
+;; Public License 1.0 (http://www.opensource.org/licenses/cpl1.0.php)
+;; which can be found in the file CPL.TXT at the root of this
+;; distribution.  By using this software in any fashion, you are
+;; agreeing to be bound by the terms of this license.  You must not
+;; remove this notice, or any other, from this software.
+
+
+;; This file defines some convenience functions for using the Java
+;; logging framework from Clojure.  It is oriented towards simple
+;; development and debugging rather than complex production
+;; environments.
+
+
+
+(ns clojure.contrib.javalog
+            (:import 
+             (java.util.logging Logger Level ConsoleHandler
+                                FileHandler SimpleFormatter)))
+
+(def 
+ #^{:tag Logger
+    :doc "The current java.util.logging.Logger.  By default, the
+          global logger, modified by 'with-logger'."}
+ *logger*
+ (. Logger
+    (getLogger
+     (. Logger GLOBAL_LOGGER_NAME))))
+
+(defmacro log-level
+  "Translates 'level' (a lower-case keyword) into a static field of
+  java.util.logging.Level, by name.  
+
+  Example: (log-level :severe)  =>  java.util.logging.Level.SEVERE
+
+  If 'level' is not a keyword, it is assumed to be a user-defined
+  instance of java.util.logging.Level and is returned unchanged."
+  [level]
+  (if (keyword? level)
+    `(. java.util.logging.Level
+        ~(symbol (. (name level) (toUpperCase))))
+    level))
+
+(defn root-logger
+  "Returns the root Logger instance."
+  ([] (root-logger *logger*))
+  ([logger] (let [parent (. logger (getParent))]
+              (if parent 
+                (recur parent) 
+                logger))))
+
+(defn set-console-log-level 
+  "Attempts to set the level of the current logger and the root
+  ConsoleHandler to 'level' (a java.util.logging.Level).  Useful for
+  debugging at the REPL."
+  [level]
+  (let [console-handler 
+        (some (fn [h] (if (instance? ConsoleHandler h) h))
+              (. (root-logger) (getHandlers)))]
+    (if console-handler
+      (do (. *logger* (setLevel level))
+          (. console-handler (setLevel level)))
+      (throw (new Exception "No ConsoleHandler on root logger.")))))
+
+(defn add-log-file
+  "Attaches a log file, using SimpleFormatter, with the given level,
+  to the named logger.  'level' defaults to ALL.  Note: multiple
+  invocations will create multiple log files, with numbers appended to
+  the names."
+  ([logger-name filename]
+     (add-log-file logger-name filename (. Level ALL)))
+  ([logger-name filename level]
+     (let [logger (. Logger (getLogger logger-name))
+           handler (new FileHandler filename)]
+       (. handler (setFormatter (new SimpleFormatter)))
+       (. handler (setLevel level))
+       (. logger (addHandler handler)))))
+
+(defmacro with-logger
+  "Executes 'body' with *logger* bound to a logger with the given name
+  and level.  'level' is expanded with 'log-level'."
+  [logger-name level & body]
+  `(binding [*logger* (. Logger (getLogger ~logger-name))]
+     (. *logger* (setLevel (log-level ~level)))
+     ~@body))
+
+(defmacro log
+  "Logs a message to *logger*.  'level' is expanded with 'log-level'.
+  Example: (log :severe \"Bad argument: \" object)" 
+  [level & strings]
+  `(. *logger* (log (log-level ~level) (str ~@strings))))