如何做到在F＃中链接的回调？ [英] How to do chained callbacks in F#?

问题描述

在C＃中，我使用的TcpListener / TcpClient的异步版本，而我这些链接通过回调方法，以便另一个接受/回调完成读取时发布。下面是一个例子（未经测试）：

In C# I am using the asynchronous versions of TcpListener/TcpClient, and I am chaining these via the callback method so that another Accept/Read is posted when the callback completes. Here is an example (untested):

    public void Start()
    {
        TcpListener listener = new TcpListener(IPAddress.Any, 3000);
        listener.Start();

        PostAccept(listener);
    }

    private void PostAccept(TcpListener listener)
    {
        listener.BeginAcceptTcpClient(AcceptCallback, listener);
    }

    private void AcceptCallback(IAsyncResult ar)
    {
        var listener = ar.AsyncState as TcpListener;

        if (listener == null)
        {
            return;
        }

        // get the TcpClient and begin a read chain in a similar manner

        PostAccept(listener);
    }

我的问题是我怎么在模型F＃类似的东西？我会用async关键字？是BeginAcceptTcpClient，的BeginRead，等以后code ..基本上是code，将在回调函数来执行？例如，这是正确的？

My question is how do I model something similar in F#? Would I use the async keyword? Is the code after BeginAcceptTcpClient, BeginRead, etc.. essentially the code that would be executed in the callback function? For example, is this correct?

let accept(listener:TcpListener) = async {      
  let! client = listener.AsyncAcceptTcpClient()    
  // do something with the TcpClient such as beginning a Read chain
  accept(listener)
  return()
}

因为它不是一个递归方法

以上code不起作用，因为接受的是没有定义，并将其标记在技术上递归是不是真的？

The above code doesn't work because accept isn't defined, and marking it recursive technically isn't true as it isn't a recursive method?

推荐答案

我不知道你所说的它不是一个recusive方法的意思;如果从它自己的定义范围内是指一个函数，那么它是一个递归函数。我没有太多的经验与套接字类，但也许这些方针的东西是你在找什么？

I'm not sure what you mean by "it isn't a recusive method"; if you refer to a function from within its own definition, then it is a recursive function. I don't have much experience with the Sockets classes, but perhaps something along these lines is what you're looking for?

let rec accept(t : TcpListener) =
  async {
    let! client = t.AsyncAcceptTcpClient()

    // do some stuff with client here

    do! accept(t)
  }

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