將clojure的* out *重定向到core.async頻道

Question

我試圖讓clojure程序中的所有打印語句將它們的字符串放在core.async頻道上。有什麼辦法可以做到這一點？

（我試圖讓cljsbuild其編譯器消息發送到前端。）

Answer 1

(def is (java.io.PipedInputStream.)) 
(def os (java.io.PipedOutputStream. is)) 

(def channel (chan)) 

(.start (Thread. (fn [] 
        (let [buffer (byte-array 1024)] 
        (while true 
         (let [n (.read is buffer 0 1024)] 
         (>!! channel (vec (take n buffer))))))))) 

(binding [*out* (java.io.OutputStreamWriter. os)] 
    (println "Hello, world!")) 

Answer 2

gfredericks給了我在#clojure IRC此引用。他建議我適應什麼nREPL做：

(defn- session-out 
    "Returns a PrintWriter suitable for binding as *out* or *err*. All of 
    the content written to that PrintWriter will (when .flush-ed) be sent on the 
    given transport in messages specifying the given session-id. 
    `channel-type` should be :out or :err, as appropriate." 
    [channel-type session-id transport] 
    (let [buf (clojure.tools.nrepl.StdOutBuffer.)] 
    (PrintWriter. (proxy [Writer] [] 
        (close [] (.flush ^Writer this)) 
        (write [& [x ^Integer off ^Integer len]] 
         (locking buf 
         (cond 
          (number? x) (.append buf (char x)) 
          (not off) (.append buf x) 
          ; the CharSequence overload of append takes an *end* idx, not length! 
          (instance? CharSequence x) (.append buf ^CharSequence x (int off) (int (+ len off))) 
          :else (.append buf ^chars x off len)) 
         (when (<= *out-limit* (.length buf)) 
          (.flush ^Writer this)))) 
        (flush [] 
         (let [text (locking buf (let [text (str buf)] 
               (.setLength buf 0) 
               text))] 
         (when (pos? (count text)) 
          (t/send (or (:transport *msg*) transport) 
            (response-for *msg* :session session-id 
               channel-type text)))))) 
        true))) 

從nREPL source here