Code to redirect output nrepl output to a particular client repl.

gistfile1.clj

;; After connecting an nrepl client repl to an nrepl server, some
;; output will still appear on stdout from the server.

;; Try these snippets - they will both produce output on the nrepl server
;; Java libraries commonly do both these things.

(.println System/out "Hello stdout.")
(.start (Thread. #(println "Hello from a new thread.")))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Now run this code on the repl where you wish to see all output.
;; You will need to add the dependency [commons-io "2.4"] to your
;; leiningen dependencies.

(import 'org.apache.commons.io.output.WriterOutputStream)
(import 'java.io.PrintStream)

;; First, we redirect the raw stdout of the server to this repl

(System/setOut (PrintStream. (WriterOutputStream. *out*)
                             true)) ;; Auto-flush the PrintStream


;; Next, we alter the root binding of *out* so that new threads
;; send their output to THIS repl rather than the original System/out.

(alter-var-root #'*out* (fn [_] *out*))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Now the snippets from before should both send output to this repl.

(.println System/out "Hello stdout.")
(.start (Thread. #(println "Hello from a new thread.")))