有什么方法可以在C ++中强制回调 [英] What are the ways to impement callback in C++

问题描述

想象一下，我有一些网络类 CNetwork ，它有一些叫做的方法： makeNetworkRequest（int requestCode）。来自 makeNetworkRequest（int requestCode）的响应当然可以在一段时间后调用此函数。我想要的是，当响应到来时，执行这样的代码，例如：

Hi,

Imagine I have some networking class CNetwork which has some method called: makeNetworkRequest(int requestCode). The response from makeNetworkRequest(int requestCode) can of course come some time later this function was called. What I want is that, when that response arrives, to execute such code for example:

void myApp::function1()
{
CMyButton button;
button.SetText(responseFromServer.text);
button.SetTextColor(responseFromServer.color);
}

我现在想要的是来自UI的用户可能正在使用不同的请求代码调用makeNetworkRequest - 以及基于此我可能想要执行不同的功能，例如执行function2而不是function1 - 我希望能够实现上面提到的功能。

The thing I want now is that the user from UI may be calling makeNetworkRequest with different request codes -- and based on that I may want to execute different functionality, e.g., for example execute function2 instead of function1 -- and I want to be able to achieve the functionality I mentioned above.

void myApp::function2()
{
CMyEdit edit;
edit.SetText(responseFromServer.text);
}

推荐答案

有很多方法可以实现您的目标。例如：

• 一个带有函数调用的switch语句，用于每种情况的硬编码
• 一种经典的，类似于C的回调机制，就像在Windows API（参见 EnumWindowsProc [ ^ ]）。使用此方法，您必须使用静态方法，但
• 使用成员函数指针
• 使用多态，即传递实现包含该接口的接口的对象方法''函数''。不同的对象以不同的方式实现这种方法。
• ...

There are really many ways to achieve what you intend to do. For instance:

• A switch statement with function calls hard-coded for every case
• A classical, C-like callback mechanism, like the one used in Windows API (see EnumWindowsProc[^]). With this approach, you have to use static methods, though
• Using member function pointers
• Using polymorphism, that is pass an object implementing the interface containing the method ''function''. Different objects implement such method in different ways.
• ...

你可能想用 I / O完成端口 [ ^ ]



Windows套接字2.0：使用完成端口编写可扩展的Winsock应用程序 [ ^ ]



您可以使用 BindIoCompletionCallback [ ^ ]，我想你会发现这篇文章有一些兴趣： IOCPNet - Ultimate IOCP [ ^ ]



祝你好运

Espen Harlinn

You would probably like to use I/O Completion Ports[^]

Windows Sockets 2.0: Write Scalable Winsock Apps Using Completion Ports[^]

You can use BindIoCompletionCallback[^], and I guess you''ll find this article of some interest:IOCPNet - Ultimate IOCP[^]

Best regards
Espen Harlinn

查看 std： ：功能 [ ^ ]和相关的标题。

give a look to std::function[^] and related header.

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