Allow ng-model bindings to arbitrary functions

src/ng/directive/input.js

@@ -995,7 +995,16 @@ var NgModelController = ['$scope', '$exceptionHandler', '$attrs', '$element', '$
 
   // model -> value
   var ctrl = this;
-  $scope.$watch(ngModelGet, function(value) {
+  var returnValue = ngModelGet(this, $scope);
+  var watcher = isFunction(returnValue)?
+                  (function(self, locals){
+                    return returnValue.call(self);
+                  }):ngModelGet;
+  $scope.$watch(watcher, function(value) {
+
+    if (isFunction(value)) {
+      value = value();
+    }
 
     // ignore change from view
     if (ctrl.$modelValue === value) return;

src/ng/parse.js

@@ -646,13 +646,22 @@ function setter(obj, path, setValue) {
   for (var i = 0; element.length > 1; i++) {
     var key = element.shift();
     var propertyObj = obj[key];
+    if (isFunction(propertyObj)) {
+      propertyObj = propertyObj();
+    }
     if (!propertyObj) {
       propertyObj = {};
       obj[key] = propertyObj;
     }
     obj = propertyObj;
   }
-  obj[element.shift()] = setValue;
+  var key = element.shift();
+  if (isFunction(obj[key])) {
+    obj[key](setValue);
+  }
+  else {
+    obj[key] = setValue;
+  }
   return setValue;
 }
 

test/ng/directive/inputSpec.js

@@ -196,6 +196,14 @@ describe('NgModelController', function() {
       expect(ctrl.$modelValue).toBe(10);
     });
 
+    it('should set the value to $modelValue when value is a function', function() {
+      scope.$apply(function() {
+        scope.value = function() {
+          return 10;
+        };
+      });
+      expect(ctrl.$modelValue).toBe(10);
+    });
 
     it('should pipeline all registered formatters in reversed order and set result to $viewValue',
         function() {
@@ -218,7 +226,6 @@ describe('NgModelController', function() {
       expect(ctrl.$viewValue).toBe('5');
     });
 
-
     it('should $render only if value changed', function() {
       spyOn(ctrl, '$render');