在delphi / pascal中使用C ++接口 [英] Using C++ interface in delphi/pascal

问题描述

我在dll中定义了以下接口：

I have the following interface defined in a dll:

class TestInterface
{
   public: int foo(int)=0;
};

以下函数让我创建这种类型的对象：

And the following functions let's me create objects of this type:

extern "C" declspec(dllexport) TestInterface* __stdcall CreateInterface();

接口在dll中实现，我可以在C ++中使用它而没有任何问题（我是还定义了 .def 文件，以确保一切正常）。然而，当它在pascal中使用它时我遇到了问题。

以下是我在pascal中尝试使用接口的方法：

The interface is implemented in the dll and I can use it in C++ without any problems (I've also defined the .def file to make sure everything works correctly). However when it comes to using it in pascal I have problems.
Here's how I'm trying to use the Interface in pascal:

type
  myinterface = interface(IInterface)
    function foo(param1: Integer): Integer;
  end;

TMyInterface = ^myinterface;
pCreateInterface = function: TMyInterface; stdcall;

var
  CreateInterface: pCreateInterface;

在pascal中使用接口：

Using interface in pascal:

function init()
begin
  DllHandle := LoadLibrary(DLLPath);
  if DllHandle <> 0 then
  begin
    @CreateInterface := GetProcAddress(DllHandle, 'CreateInterface');
    if (@GetXYZ <> nil) then
    begin
      dllInitialized := true;
      myXYZ := CreateInterface();
      myXYZ.foo(1); // Access violation error here
    end;
  end;
end;

一切似乎都很好。调试时， CreateInterface 成功执行， myXYZ 中有一些值。但是当我尝试调用 foo 时出现访问冲突错误。

我注意到我可以从dll中调用不在任何类中的函数但不是那些在类/接口内的东西。

我做错了吗？我怎么能这样做？

我有没有办法在delphi中使用C ++ dll而不改变C ++源代码？

Everything seems to be good. When debugging, CreateInterface executes successfully and there is some value in myXYZ. But when I try to call foo I get access violation error.
I've noticed I can call functions that are not within any class from a dll but not those that are inside class/interface.
Am I doing something wrong? How can I do this?
Is there a way I can use a C++ dll in delphi without changing C++ source?

推荐答案

首先，你的Delphi代码有一个从IInterface派生的对象，你的C ++没有。

To start with, your Delphi code has an object derived from IInterface, and your C++ doesn't.

但是，我建议你读这个文章，作者：Rudy Velthuis： -

But, I'd suggest you read this article, by Rudy Velthuis:-

http ：//rvelthuis.de/articles/articles-cppobjs.html

基本上，您需要将C ++端实现为COM对象，或者'将您的C ++对象展平为C可调用函数。

Basically, you either need to implement the C++ end as a COM object, or 'flatten' your C++ objects into C callable functions.

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