Isolate Example

HTML

<div ng-app="test">
    <div ng-controller="TestCtrl">
        <title-val title="val"></title-val>     
    </div>    
</div>

JavaScript

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

app.controller('TestCtrl', function ($scope) {
    $scope.val = 'World';
});

app.factory('AlertFactory', function () {
 
    return {
        doWork: function(scope) {
            scope.title = 'Fun';    
            //scope.title = scope.val;  //notice val doesn't exist in this scope
        }
    };
    
});

app.controller('DirCtrl', function ($scope, AlertFactory) {
    AlertFactory.doWork($scope);  
});

app.directive('titleVal',function () {
    return {
        template: '<h1>Hello {{title}}</h1>',
        restrict: 'E',
        controller: 'DirCtrl',
        scope: {
            title: '='
        },
        link: function() {
        
        }
    };
   
});