Libev，如何参数传递给相关的回调 [英] Libev, How to pass arguments to relevant callbacks

问题描述

我被困在参数传递libev的情况。

一般情况下，libev接收函数封装例如 * receive_callback * ，这是确定的，但在实践中，我们需要派一个相对的 * write_callback * ，以应对特定的根据接收到的包作业。例如：

  S_RECV_MSG * pstRecvMsg =（S_RECV_MSG *）recv_buff;
开关（pstRecvMsg-＆GT; wMsgType）{
    情况1：
        ev_io_init（W，write_callback1，W-＆GT; FD，EV_WRITE）;
        打破;
    案例2：
        ev_io_init（W，write_callback2，W-＆GT; FD，EV_WRITE）;
        打破;
    案例3：
        // .......
}
 

我的问题是，如果 write_callbackX 还具有读取recv_buff的具体内容，我们如何能够通过recv_buff参数传递给callbackX？我们必须承担这里的全局变量的负担和丑？

解决方案

作者回答了自己，但在一个注释。由于该显示为未，我
张贴他的回答答案一节中闭循环。不知道是否有更好的方法......随时来解决这个问题。

问题作者说：

  

对不起，我想我得到了答案，现在，觉得汗颜我
  阅读文档的大意：

 结构my_io {
   ev_io IO;
   INT otherfd;
   无效* somedata;
   无论结构* mostinteresting;
};
// ...
结构my_io瓦;
ev_io_init（安培; w.io，my_cb的情况下，FD，EV_READ）;
 

  
  

然后，我们用my_io这样​​的：

 静态无效my_cb的情况下（结构ev_loop *循环，ev_io * W_，诠释revents中）
{
   结构my_io * W =（结构my_io *）W_;
   // ...
}
 

I'm trapped in a situation of argument passing in libev.

Usually, libev receives packages in a function like *receive_callback*, that's OK, but in practice, we need to dispatch a relative *write_callback* to deal with specific jobs according to the received package. For example:

S_RECV_MSG* pstRecvMsg = (S_RECV_MSG*) recv_buff;
switch(pstRecvMsg->wMsgType) {
    case 1: 
        ev_io_init(w, write_callback1, w->fd, EV_WRITE);
        break;
    case 2:
        ev_io_init(w, write_callback2, w->fd, EV_WRITE);
        break;
    case 3:
        // .......
}

My question is, if the write_callbackX also has to read the specific content in the recv_buff, how can we pass the recv_buff argument to the callbackX? Must we bear the burden and ugliness of global variables here?

解决方案

The author answered it himself, but in a comment. Since this shows up as unanswered, I am posting his answer in the "answer" section and closing the loop. Not sure if there is a better way... feel free to fix this.

Question author says:

Sorry, I think I got the answer now, and feel deeply ashamed at my carelessness of reading documentation:

struct my_io{
   ev_io io;
   int otherfd;
   void *somedata;
   struct whatever *mostinteresting;
};
// ...
struct my_io w;
ev_io_init (&w.io, my_cb, fd, EV_READ);

And then we use the my_io like this:

static void my_cb (struct ev_loop *loop, ev_io *w_, int revents)
{
   struct my_io *w = (struct my_io *)w_;
   //...
}

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