在WinMain中可以将主窗口过程作为lambda吗? [英] can I have main window procedure as a lambda in WinMain?

问题描述

我有一个带有声明的主窗口回调过程的简单窗口应用程序:

I have a simple window application with declared main window callback procedure:

WNDCLASSEXW wcx;
/* ... */
wcx.lpfnWndProc = MainWndProc;

，并且在WinMain之后我声明了LRESULT CALLBACK MainWndProc(HWND mainWindow, UINT msg, WPARAM wparam, LPARAM lparam) { /* ... */}并且一切正常，但是我想知道是否可以将此MainWndProc作为lambda 内置在 WinMain中?

and after the WinMain I declared LRESULT CALLBACK MainWndProc(HWND mainWindow, UINT msg, WPARAM wparam, LPARAM lparam) { /* ... */} and all is working ok, but I wonder is it possible to have this MainWndProc as a lambda inside WinMain ?

推荐答案

您可以使用lambda，只要它没有捕获，然后就隐式转换为函数指针:

You can use a lambda, provided it has no captures then it has an implicit conversion to function pointer:

#include <iostream>

typedef void (*func)();

static func some_func;

int global;

int main() {
  some_func = [](){ std::cout << "Hello\n"; }; // Fine
  some_func(); 
  int local;
  some_func = [&](){ local = 1; }; // Illegal - No conversion
  some_func = [](){ global = 1; }; // Fine
}

问题实际上是，您可以在lambda中做多少事来作为没有捕获的回调.您仍然可以使用全局变量"，就像使用常规函数作为回调一样.

The problem really is how much you can usefully do in a lambda as a callback without captures. You can still resort to "globals", in the same way you might with a regular function as the callback.

这篇关于在WinMain中可以将主窗口过程作为lambda吗?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！