Hijacking System.out with Clojure

with-system-out-str.clj

(defmacro with-system-out-str
	[& body]
	`(let [out# System/out
	       buf# (java.io.ByteArrayOutputStream.)
	       prs# (java.io.PrintStream. buf#)
	       wtr# (java.io.OutputStreamWriter. prs#)]
	   (try
	     (System/setOut prs#)
	     (binding [*out* wtr#]
	       (do ~@body))
	     (finally
	       (.flush wtr#)
	       (.flush prs#)
	       (System/setOut out#)))
	   (.toString buf#)))

(with-system-out-str (.print System/out "hi") (println" there"))
;; "hi there\n"