pprint now flushes the underlying stream similarly to prn. pprint was using .flush as a method to push and reset its own internal data, but not to flush the underlying stream. The current .flush functionality has been moved into a .ppflush method, and .flush now additionally flushes the underlying stream.

djpowell · Stuart Sierra · commit 1588ff3f70e8 · 2012-11-14T10:22:29.000-05:00
Signed-off-by: Stuart Sierra &lt;mail@stuartsierra.com&gt;
diff --git a/src/clj/clojure/pprint/column_writer.clj b/src/clj/clojure/pprint/column_writer.clj
@@ -58,6 +58,8 @@
      (let [fields (ref {:max max-columns, :cur 0, :line 0 :base writer})]
        (proxy [Writer IDeref] []
          (deref [] fields)
+         (flush []
+           (.flush writer))
          (write
           ([^chars cbuf ^Integer off ^Integer len] 
              (let [^Writer writer (get-field this :base)] 
diff --git a/src/clj/clojure/pprint/pprint_base.clj b/src/clj/clojure/pprint/pprint_base.clj
@@ -164,7 +164,7 @@ radix specifier is in the form #XXr where XX is the decimal value of *print-base
                       (make-pretty-writer base-writer# *print-right-margin* *print-miser-width*)
                       base-writer#)]
        ~@body
-       (.flush *out*))))
+       (.ppflush *out*))))
 
 
 ;;;TODO: if pretty print is not set, don't use pr but rather something that respects *print-base*, etc.
diff --git a/src/clj/clojure/pprint/pretty_writer.clj b/src/clj/clojure/pprint/pretty_writer.clj
@@ -380,7 +380,7 @@
                      :miser-width miser-width
                      :trailing-white-space nil
                      :pos 0})]
-    (proxy [Writer IDeref] []
+    (proxy [Writer IDeref PrettyFlush] []
       (deref [] fields)
 
       (write 
@@ -408,13 +408,17 @@
             Long
             (p-write-char this x))))
 
-      (flush []
+      (ppflush []
              (if (= (getf :mode) :buffering)
-               (dosync 
+               (dosync
                 (write-tokens this (getf :buffer) true)
                 (setf :buffer []))
                (write-white-space this)))
 
+      (flush []
+             (.ppflush this)
+             (.flush (getf :base)))
+
       (close []
              (.flush this)))))
 
diff --git a/src/clj/clojure/pprint/utilities.clj b/src/clj/clojure/pprint/utilities.clj
@@ -102,3 +102,6 @@ beginning of aseq"
   `(prerr ~@(cons (list 'quote prefix) (mapcat #(list (list 'quote %) "=" %) 
                                                   (cons arg (seq more-args))))))
 
+;; Flush the pretty-print buffer without flushing the underlying stream
+(definterface PrettyFlush
+  (^void ppflush []))
diff --git a/test/clojure/test_clojure/pprint.clj b/test/clojure/test_clojure/pprint.clj
@@ -10,7 +10,7 @@
 
 (ns clojure.test-clojure.pprint
   (:refer-clojure :exclude [format])
-  (:use [clojure.test :only (deftest are run-tests)]
+  (:use [clojure.test :only (deftest is are run-tests)]
         [clojure.test-helper :only [platform-newlines]]
         clojure.test-clojure.pprint.test-helper
         clojure.pprint))
diff --git a/test/clojure/test_clojure/pprint/test_pretty.clj b/test/clojure/test_clojure/pprint/test_pretty.clj
@@ -326,3 +326,49 @@ It is implemented with a number of custom enlive templates.\"
   "[1, 2, 3, 4, 5, 6]\n"
   )
 
+(defn- flush-alerting-writer
+  [o]
+  (let [flush-count-atom (atom 0)]
+    [
+      (proxy [java.io.BufferedWriter] [o]
+        (flush []
+          (proxy-super flush)
+          (swap! flush-count-atom inc)))
+      flush-count-atom]))
+
+(deftest test-flush-underlying-prn
+  []
+  (let [[out flush-count-atom] (flush-alerting-writer (java.io.StringWriter.))]
+    (binding [*out* out
+              *flush-on-newline* true]
+      (prn (range 50))
+      (prn (range 50)))
+    (is (= @flush-count-atom 2) "println flushes on newline")))
+
+(deftest test-flush-underlying-pprint
+  []
+  (let [[out flush-count-atom] (flush-alerting-writer (java.io.StringWriter.))]
+    (binding [*out* out
+              *flush-on-newline* true]
+      (pprint (range 50))
+      (pprint (range 50)))
+    (is (= @flush-count-atom 2) "pprint flushes on newline")))
+
+(deftest test-noflush-underlying-prn
+  []
+  (let [[out flush-count-atom] (flush-alerting-writer (java.io.StringWriter.))]
+    (binding [*out* out
+              *flush-on-newline* nil]
+      (prn (range 50))
+      (prn (range 50)))
+    (is (= @flush-count-atom 0) "println flushes on newline")))
+
+(deftest test-noflush-underlying-pprint
+  []
+  (let [[out flush-count-atom] (flush-alerting-writer (java.io.StringWriter.))]
+    (binding [*out* out
+              *flush-on-newline* nil]
+      (pprint (range 50))
+      (pprint (range 50)))
+    (is (= @flush-count-atom 0) "pprint flushes on newline")))
+
