I have a directive of stripe, Which passing a value a from directive to controller.
Directive
angular.module('stripe', []).directive('stripeForm', ['$window',
function($window) {
  var directive = { restrict: 'A' };
  directive.link = function(scope, element, attributes) {
    var form = angular.element(element);
    form.bind('submit', function() {
      var button = form.find('button');
      button.prop('disabled', true);
      $window.Stripe.createToken(form[0], function() {
        button.prop('disabled', false);
        var args = arguments;
        scope.$apply(function() {
          scope.$eval(attributes.stripeForm).apply(scope, args);
        });
      });
    });
  };
  return directive;
}]);
Controller :
angular.module('myApp', ['stripe'])
.controller('IndexController', function($scope, $http) {
  $scope.saveCustomer = function(status, response) {
    $http.post('/save_customer', { token: response.id });
  };
});
HTML
<form stripe:form="saveCustomer">
  <fieldset>
    <input type="text" size="20" data-stripe="number"/>
    <input type="text" size="4" data-stripe="cvc"/>
    <input type="text" size="2" data-stripe="exp-month"/>
    <input type="text" size="4" data-stripe="exp-year"/>
  </fieldset>
  <button type="submit">Save</button>
</form>
One of my college says using $eval is not a best practice, So I need a alternative to replace scope.$eval. 
I also wondering that how the directive is passing value to controller. Pleae explain the code, How it works.
scope.$apply(function() {
   scope.$eval(attributes.stripeForm).apply(scope, args);
});
 
     
    