From 12c7cb07b23ea3adcbb9313a9673b2ce15ad055d Mon Sep 17 00:00:00 2001
From: Tim Schaub <tim.schaub@gmail.com>
Date: Mon, 26 Nov 2007 23:45:43 +0000
Subject: [PATCH] extend now only sets defined properties on the destination -
 if your source has a property set to undefined, the destination property will
 not be set (closes #1160).

git-svn-id: http://svn.openlayers.org/trunk/openlayers@5281 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
---
 lib/OpenLayers/Util.js | 8 ++++++--
 tests/test_Util.html   | 9 ++++++---
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/lib/OpenLayers/Util.js b/lib/OpenLayers/Util.js
index 1743b56a28..6fd439e561 100644
--- a/lib/OpenLayers/Util.js
+++ b/lib/OpenLayers/Util.js
@@ -38,7 +38,8 @@ if ($ == null) {
 /**
  * APIFunction: extend
  * Copy all properties of a source object to a destination object.  Modifies
- *     the passed in destination object.
+ *     the passed in destination object.  Any properties on the source object
+ *     that are set to undefined will not be (re)set on the destination object.
  *
  * Parameters:
  * destination - {Object} The object that will be modified
@@ -50,7 +51,10 @@ if ($ == null) {
 OpenLayers.Util.extend = function(destination, source) {
     if(destination && source) {
         for(var property in source) {
-            destination[property] = source[property];
+            value = source[property];
+            if(value !== undefined) {
+                destination[property] = value;
+            }
         }
         /**
          * IE doesn't include the toString property when iterating over an object's
diff --git a/tests/test_Util.html b/tests/test_Util.html
index 8885d8fcde..fb4659c32d 100644
--- a/tests/test_Util.html
+++ b/tests/test_Util.html
@@ -591,7 +591,7 @@
     }
 
     function tests_Util_extend(t) {
-        t.plan(5);
+        t.plan(6);
 
         var source = {
             num: Math.random(),
@@ -603,9 +603,10 @@
             },
             toString: function() {
                 return "source";
-            }
+            },
+            nada: undefined
         };
-        var destination = OpenLayers.Util.extend({}, source);
+        var destination = OpenLayers.Util.extend({nada: "untouched"}, source);
         t.eq(destination.num, source.num,
              "extend properly sets primitive property on destination");
         t.eq(destination.obj, source.obj,
@@ -614,6 +615,8 @@
              "extend properly sets function property on destination");
         t.eq(destination.toString(), "source",
              "extend properly sets custom toString method");
+        t.eq(destination.nada, "untouched",
+             "undefined source properties don't clobber existing properties");
         t.eq(window.property, undefined, "Property variable not clobbered.");
     }