[FEATURE] New CP syntax

features.json

@@ -15,7 +15,8 @@
     "ember-metal-injected-properties": null,
     "mandatory-setter": "development-only",
     "ember-routing-fire-activate-deactivate-events": null,
-    "ember-testing-pause-test": null
+    "ember-testing-pause-test": null,
+    "improved-cp-syntax": null
   },
   "debugStatements": [
     "Ember.warn",

packages/ember-metal/lib/computed.js

@@ -500,7 +500,7 @@ ComputedPropertyPrototype.teardown = function(obj, keyName) {
   The function should accept two parameters, key and value. If value is not
   undefined you should set the value first. In either case return the
   current value of the property.
-  
+
   A computed property defined in this way might look like this:
 
   ```js
@@ -516,7 +516,7 @@ ComputedPropertyPrototype.teardown = function(obj, keyName) {
   var client = Person.create();
 
   client.get('fullName'); // 'Betty Jones'
-  
+
   client.set('lastName', 'Fuller');
   client.get('fullName'); // 'Betty Fuller'
   ```
@@ -539,21 +539,41 @@ ComputedPropertyPrototype.teardown = function(obj, keyName) {
   @method computed
   @for Ember
   @param {String} [dependentKeys*] Optional dependent keys that trigger this computed property.
-  @param {Function} func The computed property function.
+  @param {Function} opts The computed property function.
   @return {Ember.ComputedProperty} property descriptor instance
 */
-function computed(func) {
-  var args;
+function computed(opts) {
+  var args, func;
 
   if (arguments.length > 1) {
     args = a_slice.call(arguments);
-    func = args.pop();
+    opts = args.pop();
+  }
+
+  if (Ember.FEATURES.isEnabled('improved-cp-syntax')){
+    if (typeof opts === "object"){
+      if (opts.set){
+        func = function(keyName, value, oldValue){
+          if (arguments.length > 1){
+            return opts.set.call(this, keyName, value, oldValue);
+          } else {
+            return opts.get.call(this, keyName);
+          }
+        };
+      } else {
+        func = opts.get;
+      }
+    } else if (typeof opts === "function"){
+      func = opts;
+      Ember.deprecate("Using the same function as getter and setter is deprecated. Pass an object containing `get` and `set` properties instead", func.length < 2);
+    }
   }
 
+  func = func || opts;
+
   if (typeof func !== "function") {
     throw new EmberError("Computed Property declared without a property function");
   }
-
   var cp = new ComputedProperty(func);
 
   if (args) {

packages/ember-metal/tests/computed_test.js

@@ -591,6 +591,66 @@ testBoth('chained dependent keys should evaluate computed properties lazily', fu
 });
 
 
+// ..........................................................
+// FEATURE 'improved-cp-syntax'
+//
+
+if (Ember.FEATURES.isEnabled('ember-metal-injected-properties')){
+  QUnit.module('computed - improved cp syntax');
+
+  test('setter and getters are passed using an object', function() {
+    var testObj = Ember.Object.extend({
+      a: '1',
+      b: '2',
+      aInt: computed('a', {
+        get: function(keyName){
+          equal(keyName, 'aInt', 'getter receives the keyName');
+          return parseInt(this.get('a'));
+        },
+        set: function(keyName, value, oldValue){
+          equal(keyName, 'aInt', 'setter receives the keyName');
+          equal(value, 123, 'setter receives the new value');
+          equal(oldValue, 1, 'setter receives the old value');
+          this.set('a', ""+value); // side effect
+          return parseInt(this.get('a'));
+        }
+      })
+    }).create();
+
+    ok(testObj.get('aInt') === 1, 'getter works');
+    testObj.set('aInt', 123);
+    ok(testObj.get('a') === '123', 'setter works');
+    ok(testObj.get('aInt') === 123, 'cp has been updated too');
+  });
+
+  test('setter can be omited', function() {
+    var testObj = Ember.Object.extend({
+      a: '1',
+      b: '2',
+      aInt: computed('a', {
+        get: function(keyName){
+          equal(keyName, 'aInt', 'getter receives the keyName');
+          return parseInt(this.get('a'));
+        }
+      })
+    }).create();
+
+    ok(testObj.get('aInt') === 1, 'getter works');
+    ok(testObj.get('a') === '1');
+    testObj.set('aInt', '123');
+    ok(testObj.get('aInt') === '123', 'cp has been updated too');
+  });
+
+  test('Passing a function that acts both as getter and setter is deprecated', function() {
+    var regex = /Using the same function as getter and setter is deprecated/;
+    expectDeprecation(function(){
+      Ember.Object.extend({
+        aInt: computed('a', function(keyName, value, oldValue){})
+      });
+    }, regex);
+  });
+}
+
 // ..........................................................
 // BUGS
 //