add *print-namespace-maps* flag to control namespace map printing - false by default, but true by default in the repl

Signed-off-by: Rich Hickey <[email protected]>

Author: puredanger

src/clj/clojure/core_print.clj

@@ -38,6 +38,12 @@
 
 (def ^:dynamic *verbose-defrecords* false)
 
+(def ^:dynamic
+ ^{:doc "*print-namespace-maps* controls whether the printer will print
+  namespace map literal syntax. It defaults to true."
+   :added "1.9"}
+ *print-namespace-maps* false)
+
 (defn- print-sequential [^String begin, print-one, ^String sep, ^String end, sequence, ^Writer w]
   (binding [*print-level* (and (not *print-dup*) *print-level* (dec *print-level*))]
     (if (and *print-level* (neg? *print-level*))
@@ -240,10 +246,12 @@
 
 (defmethod print-method clojure.lang.IPersistentMap [m, ^Writer w]
   (print-meta m w)
-  (let [[ns lift-map] (lift-ns m)]
-    (if ns
-      (print-prefix-map (str "#:" ns) lift-map pr-on w)
-      (print-map m pr-on w))))
+  (if *print-namespace-maps*
+    (let [[ns lift-map] (lift-ns m)]
+      (if ns
+        (print-prefix-map (str "#:" ns) lift-map pr-on w)
+        (print-map m pr-on w)))
+    (print-map m pr-on w)))
 
 (defmethod print-dup java.util.Map [m, ^Writer w]
   (print-ctor m #(print-map (seq %1) print-dup %2) w))

src/clj/clojure/main.clj

@@ -74,6 +74,7 @@
              *print-meta* *print-meta*
              *print-length* *print-length*
              *print-level* *print-level*
+             *print-namespace-maps* true
              *data-readers* *data-readers*
              *default-data-reader-fn* *default-data-reader-fn*
              *compile-path* (System/getProperty "clojure.compile.path" "classes")

test/clojure/test_clojure/printer.clj

@@ -134,4 +134,6 @@
                                       (ex-info "the root"
                                                {:with "even" :more 'data})))))))
 
-
+(deftest print-ns-maps
+  (is (= "#:user{:a 1}" (binding [*print-namespace-maps* true] (pr-str {:user/a 1}))))
+  (is (= "{:user/a 1}" (binding [*print-namespace-maps* false] (pr-str {:user/a 1})))))