Since Angular 1.5 it's possible to use Components. Components are the-way-to-go and solves this problem easy.
<myComponent data-ng-model="$ctrl.result"></myComponent>
app.component("myComponent", {
templateUrl: "yourTemplate.html",
controller: YourController,
bindings: {
ngModel: "="
}
});
Inside YourController all you need to do is:
this.ngModel = "x"; //$scope.$apply("$ctrl.ngModel"); if needed