Add hook for modifying the merge behavior of $.extend. Specifically, and time there...

diff --git a/src/jquery/jquery.js b/src/jquery/jquery.js
index 715fbf11016255869b0e686ffa0d17cc14a12432..5347c9265345628ce9689d7d166759e3d628db54 100644 (file)
--- a/src/jquery/jquery.js
+++ b/src/jquery/jquery.js
@@ -1177,6 +1177,10 @@ jQuery.fn = jQuery.prototype = {
 /**
  * Extend one object with one or more others, returning the original,
  * modified, object. This is a great utility for simple inheritance.
+ *
+ * There is also an optional collision resolution function. Any time the target and
+ * merged object both contain a key this function is called. This may be used to create
+ * a recursive merge. (See example) Unless you know what this is, you probably don't care.
  * 
  * @example var settings = { validate: false, limit: 5, name: "foo" };
  * var options = { validate: true, name: "bar" };
@@ -1190,8 +1194,19 @@ jQuery.fn = jQuery.prototype = {
  * @result settings == { validate: true, limit: 5, name: "bar" }
  * @desc Merge defaults and options, without modifying the defaults
  *
+ * @example var defaults = { validate: false, limit: 5, name: "foo", nested: {depth: false} };
+ * var options = { validate: true, name: "bar", nested: {depth: true} };
+ * var collision_resolver_fn = function(target, mergee) {
+ *   // combine nested Objects, in this case the object being merged takes priority
+ *   return jQuery.extend({}, target, mergee);
+ * }
+ * var settings = jQuery.extend({}, collision_resolver_fn, defaults, options);
+ * @result settings == { validate: true, limit: 5, name: "bar" }
+ * @desc Recursively merge defaults and options, without modifying the defaults
+ *
  * @name $.extend
  * @param Object target The object to extend
+ * @param Function (optional) collision resolution function. Hook to extend the merging behavior of $.extend(). See example.
  * @param Object prop1 The object that will be merged into the first.
  * @param Object propN (optional) More objects to merge into the first
  * @type Object
@@ -1199,18 +1214,26 @@ jQuery.fn = jQuery.prototype = {
  */
 jQuery.extend = jQuery.fn.extend = function() {
        // copy reference to target object
-       var target = arguments[0],
+       var resolver, prop, target = arguments[0],
                a = 1;
-
+       
        // extend jQuery itself if only one argument is passed
        if ( arguments.length == 1 ) {
                target = this;
                a = 0;
+       } else if (jQuery.isFunction(arguments[a])) {
+         resolver = arguments[a++];
        }
-       var prop;
+
        while (prop = arguments[a++])
                // Extend the base object
-               for ( var i in prop ) target[i] = prop[i];
+               for ( var i in prop ) {
+                 if (resolver && target[i] && prop[i]) {
+                   target[i] = resolver(target[i], prop[i]);
+           } else {
+                   target[i] = prop[i];
+                 }
+         }
 
        // Return the modified object
        return target;