Node.js连接createServer代码 [英] Node.js Connect createServer code

问题描述

我正在阅读Node.js Connect版本2.15.0：

I'm reading Node.js Connect version 2.15.0:

/**
 * Create a new connect server.
 *
 * @return {Function}
 * @api public
 */

function createServer() {
  function app(req, res, next){ app.handle(req, res, next); }
  utils.merge(app, proto);
  utils.merge(app, EventEmitter.prototype);
  app.route = '/';
  app.stack = []; 
  for (var i = 0; i < arguments.length; ++i) {
    app.use(arguments[i]);
  }
  return app;
};

几个问题：

1. app.handle 似乎是原始提供的，因为有
   app.handle 。因此，这是对闭包的使用，
和 app.handle 的定义不是在节点解析函数
时定义的app（），但稍后在代码中？此外， app 本身也在..uh中定义为
。. function app（）。该代码对我来说似乎很有趣。

1. app.handle seems to be provided in proto, since there is app.handle defined in proto.js. So, this is a use of a closure, and app.handle is defined not at the time Node parses function app() but later on in the code? Also app itself is defined in..uh..function app(). The code seems funny to me.

何时调用函数app（）？我所知道的创建服务器会创建
服务器。那么，什么时候调用该函数？我
是否会执行以下操作：

When is function app() invoked? All I know create server creates the server. So when would I be invoking that function and how? Do I do something like:

app = createServer()
app.listen(3000)
app(req, res, next)

utils.merge（）简单地说

utils.merge() simply says

exports.merge = function(a, b){ 
  if (a && b) {
    for (var key in b) {
      a[key] = b[key];
    }   
  }
  return a;
};

这是代替继承还是一种常见的做法吗？在我看来， mixin 。

Is that a common practice to do instead of inheritance or what? It looks like mixin to me.

推荐答案

1. app.handle 似乎是原始提供的，因为有
   proto.js中定义的 app.handle 。因此，这是闭包的用法，
   和 app.handle 的定义不是在Node解析 function app（）<时定义的。 / code>
，但是稍后在代码中呢？此外， app 本身也在..uh中定义为
。. function app（）。该代码对我来说似乎很有趣。



1. app.handle seems to be provided in proto, since there is app.handle defined in proto.js. So, this is a use of a closure, and app.handle is defined not at the time Node parses function app() but later on in the code? Also app itself is defined in..uh..function app(). The code seems funny to me.

是， app.handle 来自 proto 。但是不，访问 app 函数内的 app 不是闭包，在所有函数中按其名称提供函数

Yes, app.handle comes from proto. But no, accessing app inside the app function is not a closure, a function is available by its name in all function declarations.

2。什么时候调用 function app（）？我所知道的 createServer 创建
服务器。那么什么时候调用该函数以及如何调用？

2. When is function app() invoked? All I know createServer creates the server. So when would I be invoking that function and how?

连接文档使用以下示例代码：

var app = connect();
…
http.createServer(app).listen(3000);

您可以看到 connect （即<您发布的 createServer 函数）确实创建了 app ，并将其作为处理程序传递给实际的http服务器。 / p>

You can see that connect (which is the createServer function you posted) does create the app, which is passed as a handler to the actual http server.

3。 utils.merge（）是常见的做法而不是继承吗？对我来说，这似乎是 mixin 。

3. Is utils.merge() a common practice instead of inheritance or what? It looks like mixin to me.

是， merge 确实将一个对象混入另一个对象。这样做是为了使用所有必需的方法扩展功能对象 app 。这是必要的，因为不可能以标准方式使用原型链定义功能。他们可能也使用了类似的方式：

Yes, merge does mixin one object into the other. This is done to extend the function object app with all the necessary methods. It is necessary because it is impossible to Define a function with a prototype chain in a standard way. They might have used something along these lines as well:

app.__proto__ = utils.merge(Object.create(EventEmitter.prototype), proto);

，但是 app 不再是 instanceof Function ;并且没有函数方法。

but then app wouldn't any longer be instanceof Function; and have no function methods.

这篇关于Node.js连接createServer代码的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！