AngularJS: Access directive's isolated scope from parent controller

Question

I want to write a directive with isolated scope but also want to make that scope available for the parent scope\'s controller. I found this solution:

Answer 1

To maintain proper separation of concerns, you should not mix scopes. Not to mention that it will be hard to synchronize. To summarize: your directive should not know anything about the parent scope (or its controller) and your controller should not know anything about a directive's internals. They are separate components in separate layers.

The proper way to communicate between a controller and a directive is through directive attributes. In the case of a popup, say, this can be done with a simple boolean value.

The controller and directive:

app.directive('popupbutton', [function() {
  return {
    restrict: "E",
    scope: { isOpen: "=" },
    template: 'Toggle
Open? {{isOpen}}'
  };
}]);

app.controller('MainCtrl', function($scope) {
  $scope.isOpen = false;
});

And the markup:

This method requires no logic, works out of the box, and maintains clean separation of concerns. Here's an updated plunker: http://plnkr.co/edit/otIaGCLmiNdGcYEgi60f?p=preview