var util = require("util"); //导入util模块

var events = require("events"); //导入events模块

module.exports = MyStream;

function MyStream() {

    events.EventEmitter.call(this); //call方法使得MyStream对象继承了EventEmitter对象上的方法

}

util.inherits(MyStream, events.EventEmitter);   //使用inherits方法

MyStream.prototype.write = function (data) {    //MyStream对象扩展了一个write方法，它可以使用emit触发事件

    this.emit("data", data);

};

var stream = new MyStream();    //构建一个stream对象

console.log("stream instanceof events.EventEmitter: " + (stream instanceof events.EventEmitter)); //判断stream对象是不是EventEmitter对象的实例，这里为true

console.log("MyStream.super_ === events.EventEmitter: " + (MyStream.super_ === events.EventEmitter)); //MyStream的父类是不是EventEmitter，这里为true

stream.on("data", function (data) {

    console.log('Received data: "' + data + '"');

});

stream.write("It works1!");

stream.write("It works2!");