PopUp opener directive for angularjs

controller.js

"use strict";
myApp.controller("SomeCtrl", function($scope){
    $scope.callback = function(){
        // do something
    };
    $scope.url = "http://some/popup";

});

popup.directive.js

myApp.directive("popup", function($window){
    return {
        restrict: "AE",
        scope: {
            popup: "=",
            dimensions: "@",
            callback: "="
        },
        link: function(scope, elem){
            $window.comeBack = function(){
                scope.callback();
            };
            elem.on("click", function(e){
                var authwindow = $window.open(scope.popup, "popup", scope.dimensions);
                authwindow.focus();
            });
        }
    };
});

template.html

<button popup="url" callback="callback" dimensions="width=500,height=300">ExamplePopUp</button>