红宝石 - 传递方法给DLL库作为回调 [英] Ruby - passing a method to a DLL library as a callback

问题描述

让我们说我有一个C / C ++库使用该功能，编译为一个DLL：

Let's say I have a C/C++ library with this function, compiled to a DLL:

#include <Windows.h>

extern "C" __declspec(dllexport) void __stdcall myFunction(void (*myCallback)(int)) {
    int result = MessageBox(
        0, (LPCWSTR)L"Press yes or no", (LPCWSTR)L"Test", MB_YESNO
    );
    myCallback(result);
}

这只是打开标准的Win32消息框，将结果传递给一个回调函数。

It just opens standard Win32 message box and passes the result to a callback function.

现在的问题是：是否有可能使用在Ruby中此功能，通过小提琴或类似的东西，并以某种方式传递一个Ruby的方法，以便它是从C ++中调用code

The question is: is it possible to use this function in Ruby, via Fiddle or something similar, and pass a Ruby method to it somehow so it is called from within the C++ code?

下面是code我用进口的DLL库红宝石：

Here is the code I use to import DLL library to Ruby:

require "fiddle"

myLibrary = Fiddle.dlopen("myLibrary.dll")
myFunction = Fiddle::Function.new(
  myLibrary["myFunction"], 
  [Fiddle::TYPE_VOIDP], 
  Fiddle::TYPE_VOID
)

def myCallback(value)
  puts "MessageBox result is #{value}"
end

这显然是行不通的：

And this obviously doesn't work:

myFunction.call(method(:myCallback))

这只是抛出一个TypeError - 不能转换法整数

It just throws a TypeError - can't convert Method to Integer.

有没有办法来传​​递回调到C函数？

Is there a way to pass the callback to the C function?

推荐答案

于是我找到了解决办法：

So I found the solution:

myClosure = Class.new(Fiddle::Closure) {
  def call(value)
    puts "MessageBox result is #{value}"  
  end
}.new(Fiddle::TYPE_VOID, [Fiddle::TYPE_INT])

然后，我可以简单地调用C函数：

Then I can simply call the C function:

myFunction.call(myClosure)

我真的不知道这是如何工作 - 但它工作得很好。

I don't really know how this works - but it works fine.

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