[英]Interacting with a c struct containing only function pointers using ctypes in python
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). 我在一个dll中有一个结构,它只包含我想在python中与之交互的函数指针(即vtable)(用于测试目的)。 I am having a bit of trouble working out how to do this using ctypes.
我在使用ctypes来解决这个问题时遇到了一些麻烦。
What I have is: 我有的是:
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);
A 'real' Test object will fill in the struct as appropriate. “真正的”Test对象将根据需要填充结构。 This gets compiled into a DLL (test.dll).
这会被编译成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.
我想,在python中,能够调用工厂方法来获取指向我的Test结构的指针,然后调用结构中包含的函数指针,但我似乎无法理解它是怎么回事会使用ctypes。 Does anyone have any pointers / examples of doing something similar or should I be using something like SWIG or Boost?
有没有人有任何关于做类似事情的指针/例子,或者我应该使用像SWIG或Boost这样的东西?
Thanks for any help. 谢谢你的帮助。
Something like this should be a good starting point (I don't have your DLL compiled to test) 这样的事情应该是一个很好的起点(我没有编译你的DLL来测试)
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)
After this, you'll need to call make_Test() to get the struct, and try calling the functions. 在此之后,您需要调用make_Test()来获取结构,并尝试调用函数。 Perhaps with code like this:
也许使用这样的代码:
itest = test.make_Test().contents
itest.SetName('asdf')
print itest.GetName()
Provide the dll or test and give me your results and I can help more if you still have problems. 提供dll或测试并给我你的结果,如果你还有问题,我可以提供更多帮助。
The ctypes documentation says that you can create a ctypes.PYFUNCTYPE from an address. ctypes文档说您可以从地址创建ctypes.PYFUNCTYPE。
If you get the address of the functions in your structure then you can wrap it as a Python function thanks to ctypes.PYFUNCTYPE and then call it as a regular ctype function. 如果你获得了结构中函数的地址,那么你可以将它包装成Python函数,这要归功于ctypes.PYFUNCTYPE,然后将其称为常规ctype函数。
I didn't test it myself but I think it maybe something to explore in your case 我自己没有测试过,但我觉得在你的情况下可能需要探索一些东西
See http://docs.python.org/library/ctypes.html#ctypes.PYFUNCTYPE 请参阅http://docs.python.org/library/ctypes.html#ctypes.PYFUNCTYPE
I hope it helps 我希望它有所帮助
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