clojure: adding a debug trace to every function in a namespace?

Question

just started using log4j in one of my home-projects and I was just about to break out the mouse and cut-and-paste (trace (str "entering: " function-name)) into every function in a large module. then the voice of reason caught up and said "there has simply got to be a better way"... I can think of making a macro that wraps a whole block of functions and adds the traces to them or something like that? Any advice from the wise Stack-overflowing-clojurians?

Answer 1

No need for a macro:

(defn trace-ns
  "ns should be a namespace object or a symbol."
  [ns]
  (doseq [s (keys (ns-interns ns))
          :let [v (ns-resolve ns s)]
          :when (and (ifn? @v) (-> v meta :macro not))]
    (intern ns
            (with-meta s {:traced true :untraced @v})
            (let [f @v] (fn [& args]
                          (clojure.contrib.trace/trace (str "entering: " s))
                          (apply f args))))))

(defn untrace-ns [ns]
  (doseq [s (keys (ns-interns ns))
          :let [v (ns-resolve ns s)]
          :when (:traced (meta v))]
    (alter-meta! (intern ns s (:untraced (meta v)))
                 #(dissoc % :traced :untraced))))

...or something similar. The most likely extra requirement would be to use filter so as not to call trace on things which aren't ifn?s. Update: edited in a solution to that (also handling macros). Update 2: fixed some major bugs. Update 4: added untrace functionality.

Update 3: Here's an example from my REPL:

user> (ns foo)
nil
foo> (defn foo [x] x)
#'foo/foo
foo> (defmacro bar [x] x)
#'foo/bar
foo> (ns user)
nil
user> (trace-ns 'foo)
nil
user> (foo/foo :foo)
TRACE: "entering: foo"
:foo
user> (foo/bar :foo)
:foo
user> (untrace-ns 'foo)
nil
user> (foo/foo :foo)
:foo