在Swig .i文件中，如何为基于第三方mfc的dll解析ms Windows vc ++ typedef类型？

Question

I want to wrap a MFC C++ based SDK to a python module with swig. But here I think the problem involves C++ and swig only.

Problem

After compiling the .i file, when I started to build xxx_wrap.cxx, it raised an error.

error C2182: 'arg1' : illegal use of type 'void'

In cxx file, the error code is this VOID arg1 ; .

In original .h file the error code is a constructor function of a class XXXxxx( VOID );

First Try

I thought this was because swig took VOID as a complex structure. I changed the VOID in .h file to void . But after a 'successful' compiling, the python can not import the module. Because the function declaration is not the same as the one in the SDK DLL.

And the same problem happened in the LPCSTR .

cannot convert from 'char **' to 'LPCSTR *'

PS I have added the %include <windows.i> into the .i files. But still the swig takes the VOID as a complex structure.

Question

How to write a right .i file for this kind of typedef? Is there any other wrapped code example? I have searched stackoverflow and github, but got nothing.

Possible Solution

Maybe I should write typedef in .i outside %{ ... }% section for swig other than just in .h file. But I don't know how. I am currently reading the swig doc for a third time.

Restriction

• The DLL files are provided as a device SDK, and I don't have the source files.

• From the .h files, we know that the DLL is based on multiple classes.

   class A; class B; class C; class __declspec(dllexport) D { ... private: friend class A; friend class B; friend class C; } 

• I have tried the ctypes before. The import was OK, but when I called a function, it raised an exception.

  exception: access violation writing 0x1D1A9446

  I think it is because this is a C++ mumber function. The code want to access a class member variant, which is out of the range of the function. That's why ctypes doesn't work for c++ class dll.

SDK

The SDK provides 15 .h files, 17 .dll files and 4 .lib fils. It supports both unicode and multi-byte code. It use a lot of LPCSTR and other string related typedefs.

Answer 1

Not sure what the issue is with VOID , need to see more code (such as, what is VOID defined as).

About LPCSTR , it is true that you can't convert. One way to do it would be to put what is explained on C++ LPCTSTR to char* in a wrapper function in your .i. The fact that it is a char** indicates the C++ function will probably return a pointer to an internal string. Python doesn't know how to handle that so you should return a string instance. Example:

%inline %{
    std::string myFunc() // don't use char** since 
    {
         LPCTSTR pszA = ... create buffer for LPCSTR string
         callYourMFCFunc(& pszA);
         CStringA sB(pszA);
         return std::string((const char*)sB);
    }
%}

I haven't tested the above, it is my best guess based on that SO post so you might have to fix a bit but you get the idea. SWIG's %inline and %extend directives allow you to completely adapt one API to another (in this case, change a function that takes a char** as arg into a function that returns a string).