AngularJS: Share data between controllers with Service and Watchers

app.js

var myModule = angular.module('myModule', []);

myModule
  .service('dataService', function($parse) {
    var self = this;
    return {
      setData: function(data) {
        self.data = data;
      },
      getData: function() {
        return self.data;
      },
      bind: function(expr, scope) {
        var getter = $parse(expr);
        var setter = getter.assign;
        scope.$watch(function() {
          return getter(self);
        }, function() {
          setter(scope, getter(self))
        });
      }
    };
  });

myModule
  .controller('controller1', function($scope, dataService) {
    dataService.bind('data', $scope);

    $scope.setData = function() {
      dataService.setData('Controller 1');
    };
  });

myModule
  .controller('controller2', function($scope, dataService) {
    dataService.bind('data', $scope);

    $scope.setData = function() {
      dataService.setData('Controller 2');
    };
  });