var myapp = angular.module('myApp',[]);

    myapp.controller('Controller', ['$scope', function($scope) {
        $scope.isLoading = false;

     }])
    .directive('progressButton', function(){
      return {
        restrict: 'E',
        scope: {
          className: '@',
          buttonText: '@',
          loading: '='
        },
        template: '<button type="button" ng-disabled="{{loading}}" class="{{className}}">{{buttonText}}</button>'
      }
    })

// In HTML
/*
<div ng-controller="Controller">
  <progress-button loading="isLoading" button-text="Login" class-name="btn btn-primary"></progress-button>
  </div>
*/