allow evaluation contexts to opt out of pr-values printing of :value …

…slots by setting :printed-value
clojure · Mar 26, 2015 · 3875c6e · 3875c6e
1 parent 3e06bf7
commit 3875c6e
Showing 1 changed file with 23 additions and 14 deletions.
diff --git a/src/main/clojure/clojure/tools/nrepl/middleware/pr_values.clj b/src/main/clojure/clojure/tools/nrepl/middleware/pr_values.clj
@@ -11,22 +11,31 @@
    delegating all actual message handling to the provided handler.
 
    Requires that results of eval operations are sent in messages in a
-   :value slot."
+   :value slot.
+
+   If :value is already a string, and a sent message's :printed-value
+   slot contains any truthy value, then :value will not be re-printed.
+   This allows evaluation contexts to produce printed results in :value
+   if they so choose, and opt out of the printing here."
   [h]
   (fn [{:keys [op ^Transport transport] :as msg}]
-    (h (assoc msg :transport (reify Transport
-                               (recv [this] (.recv transport))
-                               (recv [this timeout] (.recv transport timeout))
-                               (send [this resp]
-                                 (.send transport
-                                   (if-let [[_ v] (find resp :value)]
-                                     (let [repr (java.io.StringWriter.)]
-                                       (assoc resp :value (do (if *print-dup*
-                                                                (print-dup v repr)
-                                                                (print-method v repr))
-                                                              (str repr))))
-                                     resp))
-                                 this))))))
+    (h (assoc msg
+         :transport (reify Transport
+                      (recv [this] (.recv transport))
+                      (recv [this timeout] (.recv transport timeout))
+                      (send [this {:keys [printed-value value] :as resp}]
+                        (.send transport
+                          (if (and printed-value (string? value))
+                            (dissoc resp :printed-value)
+                            (if-let [[_ v] (find resp :value)]
+                              (assoc resp
+                                :value (let [repl (java.io.StringWriter.)]
+                                         (if *print-dup*
+                                           (print-dup v repr)
+                                           (print-method v repr))
+                                         (str repr)))
+                              resp)))
+                        this))))))
 
 (set-descriptor! #'pr-values
   {:requires #{}