在AngularJS中，ng-controller是最常用的directive。比如：
var app = angular.module("app",[]);
app.controlle("AppCtrl", function(){
var app = this;
app.people = [
{"firstName":"", "lastName":""},
...
];
})
app.controller("FirstCtrl", function(){
var first = this;
first.message = "i am the first one";
})
app.controller("SecondCtrl", function(){
var second = this;
second.message = "i am the second one";
})
页面部分：
<body ng-controller="AppCtrl as app">
<div ng-controller="FirstCtrl as first">
{{first.message}}
</div>
<div ng-controller="SecondCtrl as second">
{{second.message}}
</div>
</body>
现在模拟一个ng-controller的directive
app.directive("myController", function(){
return {
scope: true,
controller: '@'
}
})
可见，my-controller和ng-controlller工作原理是一样的。
页面部分使用my-controller
<body my-controller="AppCtrl as app">
<div my-controller="FirstCtrl as first">
{{first.message}}
</div>
<div my-controller="SecondCtrl as second">
{{second.message}}
</div>
</body>
所有的页面呈现都不变。
如果我们想让自定义的my-controller替代AngularJS默认的ng-controller，可以使用priority属性：
app.directive("myController", function(){
return {
scope: true,
controller: '@',
priority: 500
}
})
默认的priority字段值是0.