app.directive('myDirective',function() {
    return {
        restrict: 'E',scope {
            attr1: '@',attr2: '@',noValueAttr: // what to put here?
        },link: function(scope,elem,attrs) {
            // how to check here if noValueAttr is present in mark-up?
        }
    };
});

HTML可能是

<my-directive attr1='...' attr='...' ... no-value-attr>

要么

<my-directive attr1='...' attr='...' >

我想知道如何使用(并使指令检测它是否存在)一个没有赋值的可选属性.谢谢.