angular extend $scope is it safe?

Question

This thread follow angularjs share data config between controllers

so I'm wondering if instead of copy by hand property/method is it safe doing like

.factory('MyTest',function(){
        return {
            prop: 'Mytest',
            myFunc: function(){
               alert('Hello'); 
            }
        }
    })
.controller('IndexCtrl', function ($scope,MyTest) {
       angular.extend($scope,MyTest);
       console.log($scope);
    })

Update It works of course only for property but if it's safe could be a good thing find a way to apply it also for method.

UPDATE 1

This seems to be a good way:

 'use strict';
                (function(window, angular, undefined) {
                    'use strict';
                    angular.module('ctrl.parent', [])
                        .controller('ParentController',function (scope) {
                            scope.vocalization = '';
                            scope.vocalize = function () {
                                console.log(scope.vocalization);
                            };
                    });
                })(window, angular);
                angular.module('app',['ctrl.parent'])
                    .controller('ChildCtrl', function($scope,$controller){

                     angular.extend($scope, new $controller('ParentController', {scope:$scope}));
$scope.vocalization = 'BARK BARK';
                });

credit to @marfarma

UPDATE 2

I'm wondering why this doesn't work

'use strict';
            angular.module('animal', [])
                .factory('Animal',function(){
                    return function(vocalization){
                        return {
                            vocalization:vocalization,
                            vocalize : function () {
                                console.log('vocalize: ' + this.vocalization);
                            }
                        }
                    }
                });    
                angular.module('app', ['animal'])
                    .factory('Dog', function (Animal) {
                        function ngPost() {};
                        ngPost.prototype.status = ['publish','draft'];
                        return angular.extend(Animal('bark bark!'), new ngPost());
                    })
                    .factory('Cat', function (Animal) {
                        return Animal('meeeooooow');
                    })
                .controller('MainCtrl',function($scope,Cat,Dog){
                     $scope.cat = Cat;
                     $scope.dog = Dog;
                     console.log($scope.cat);
                     console.log($scope.dog);
                    //$scope.cat = Cat;
                });

this works

.factory('Dog', function (Animal) {
                        function ngDog(){
                            this.prop = 'my prop';
                            this.myMethod = function(){
                                console.log('test');
                            }
                        }
                        return angular.extend(Animal('bark bark!'), new ngDog());
                    })

UPDATE 3

sorry to bother you again but after a while thinking of this thread I think my question was misunderstood (or I didn't explain myself clearly) what I wanted really know if doing like

angular.extend($scope,MyService)

could be bad/good practice is it breaking oop encapsulation principle ? I mean it smells like

MyService.call($scope);

and you could face variable and function conflicts

so .......

Answer 1

You can have a look at the source of the extend function and see it's safe:

function extend(dst) {
  var h = dst.$$hashKey;
  forEach(arguments, function(obj){
    if (obj !== dst) {
      forEach(obj, function(value, key){
        dst[key] = value;
      });
    }
  });

  setHashKey(dst,h);
  return dst;
}