AngularJS从指令中获取$event

如果我使用链接功能(不包括在我的小提琴中),我可以获得$event,但我无法在正确的范围内解析/ $eval它.

http://jsfiddle.net/langdonx/KgcGY/

<div ng-app="app" ng-controller="x">
    <!-- via directive -->
    <checkbox cb-model="y" cb-click="test($event,b)"></checkbox>
    <!-- via html -->
    <div><input id="c2" type="checkbox" ng-model="x" ng-click="test($event,'a')"> <label for="c2">{{x}}</label></div> 
</div>

–

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

app.directive('checkbox',function ($parse) {
    return {
        restrict: 'E',replace: true,scope: {
            cbModel: '=',cbClick: '&'
        },template: '<div><input id="c1" type="checkbox" ng-model="cbModel" ng-click="cbClick($event,'a')"> <label for="c1">{{cbModel}}</label></div>'
    };
});

app.controller('x',function x($scope) {
    $scope.x = true;
    $scope.y = true;
    $scope.test = function (ev,b) {
        console.log('test called,ev is',ev,'b is',b);
        return 'xyz';
    }
});