在python中使用ctypes与仅包含函数指针的c结构进行交互

问题描述

我在dll中有一个结构，该结构只包含我想在python中进行交互的函数指针（即vtable）（出于测试目的）。我在解决如何使用ctypes进行操作时遇到了一些麻烦。

I have a struct in a dll that only contains function pointers (ie a vtable) that I would like to interact with in python (for test purposes). I am having a bit of trouble working out how to do this using ctypes.

我所拥有的是：

struct ITest
{
    virtual char const  *__cdecl GetName() = 0;
    virtual void  __cdecl SetName(char const *name) = 0;
};

/* Factory function to create 'real' Test object */
extern "C" __declspec(dllexport) struct ITest * CALLCONV make_Test(char const * name);

真实测试对象将在相应的结构中填充。这被编译成DLL（test.dll）。我希望在python中能够调用factory方法来获取指向我的Test结构的指针，然后调用该结构中包含的函数指针，但是我似乎无法理解它的原理将使用ctypes工作。是否有人有做类似事情的指针/示例，还是我应该使用SWIG或Boost之类的东西？

A 'real' Test object will fill in the struct as appropriate. This gets compiled into a DLL (test.dll). I'd like, in python, to be able to call the factory method to get back a pointer to my Test struct and then call the function pointers contained in the struct, but I just can't seem to get my head around how it would work using ctypes. Does anyone have any pointers / examples of doing something similar or should I be using something like SWIG or Boost?

感谢您的帮助。

推荐答案

类似的东西应该是一个很好的起点（我没有编译您的DLL以进行测试）

Something like this should be a good starting point (I don't have your DLL compiled to test)

from ctypes import Structure, CFUNCTYPE, POINTER, c_char_p, windll
class ITest(Structure):
    _fields_ = [
            ('GetName', CFUNCTYPE(c_char_p)),
            ('SetName', CFUNCTYPE(None, c_char_p)
        ]

test = windll.LoadLibrary('test.dll')
test.make_Test.restype = POINTER(ITest)

之后，您需要调用make_Test（ ）以获取结构，然后尝试调用函数。

After this, you'll need to call make_Test() to get the struct, and try calling the functions. Perhaps with code like this:

itest = test.make_Test().contents
itest.SetName('asdf')
print itest.GetName()

提供dll或测试并给我你r的结果，如果您仍然有问题，我可以提供更多帮助。

Provide the dll or test and give me your results and I can help more if you still have problems.

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