Python ctypes返回函数指针数组

事情并不像人们想象的在1个那样容易ST一目了然。我将发布一个虚拟示例，该示例恰好包含使用 .dll s（ .so
s）中的函数的2种方式（如[Python 3.Docs]中所述：ctypes-
Python的外部函数库）。

dll00.c ：

#include <stdio.h>#if defined(_WIN32)#  define DLL00_EXPORT __declspec(dllexport)#  pragma warning(disable: 4477)  // !!! Just to avoid having additional pre (macro for size_t), do NOT do this !!!#else#  define DLL00_EXPORT#endif#define PRINT_MSG_0() printf("        [%s] (%d) - [%s]n", __FILE__, __LINE__, __FUNCTION__)#define PRINT_MSG_1I(ARG0) printf("        [%s] (%d) - [%s]:  ARG0: %dn", __FILE__, __LINE__, __FUNCTION__, ARG0)static int IsValidInt(int i) {    PRINT_MSG_1I(i);    return -i;}static int InvalidInt() {    PRINT_MSG_0();    return 0;}static int IsValidSize (size_t i) {    PRINT_MSG_1I(i);    return -i;}typedef struct DllInterfaceV2Struct {    int (__cdecl *IsValidIntFuncPtr)(int i);    int (__cdecl *InvalidIntFuncPtr)();    int (__cdecl *IsValidSizeFuncPtr)(size_t i);} DllInterfaceV2;static DllInterfaceV2 intfV2 = { IsValidInt, InvalidInt, IsValidSize };#if defined(__cplusplus)extern "C" {#endifDLL00_EXPORT const DllInterfaceV2 *GetInterfaceV2(int version);#if defined(__cplusplus)}#endifDLL_EXPORT const DllInterfaceV2 *GetInterfaceV2(int version) {    if (version == 2) {        return &intfV2;    } else {        return NULL;    }}

pre00.py ：

#!/usr/bin/env python3import sysimport ctypesDLL_NAME = "test00.dll"DLL_FUNC_NAME = "GetInterfaceV2"# "Define" the Python counterparts for C stuff in order to be able to use itIsValidIntFuncPtr = ctypes.CFUNCTYPE(ctypes.c_int, ctypes.c_int)InvalidIntFuncPtr = ctypes.CFUNCTYPE(ctypes.c_int)IsValidSizeFuncPtr = ctypes.CFUNCTYPE(ctypes.c_int, ctypes.c_size_t)class DllInterfaceV2(ctypes.Structure):    _fields_ = [        ("is_valid_int", IsValidIntFuncPtr),        ("invalid_int", InvalidIntFuncPtr),        ("is_valid_size", IsValidSizeFuncPtr)    ]# Now, play with C stuffdef test_interface_ptr(intf_ptr):    print("Testing returned interface: {:}n".format(intf_ptr))    if not intf_ptr:        print("    NULL pointer returned from Cn")        return    intf = intf_ptr.contents  # Dereference the pointer    res = intf.is_valid_int(-2718281)    print("    `is_valid_int` member returned: {:d}n".format(res))    res = intf.invalid_int()    print("    `invalid_int` member returned: {:d}n".format(res))    res = intf.is_valid_size(3141592)    print("    `is_valid_size` member returned: {:d}nn".format(res))def main():    test_dll = ctypes.CDLL(DLL_NAME)    get_interface_v2_func = getattr(test_dll, DLL_FUNC_NAME)  # Or simpler: test_dll.GetInterfaceV2    get_interface_v2_func.argtypes = [ctypes.c_int]    get_interface_v2_func.restype = ctypes.POINTER(DllInterfaceV2)    pintf0 = get_interface_v2_func(0)    test_interface_ptr(pintf0)    pintf2 = get_interface_v2_func(2)    test_interface_ptr(pintf2)if __name__ == "__main__":    print("Python {:s} on {:s}n".format(sys.version, sys.platform))    main()

注意事项 ：

• C 部分：

  • 我必须添加一些虚拟代码以测试和说明行为
  • 尽管您提到它不可修改，但我还是做了一些更改（主要是命名/编码风格，…）：
  • 两个字母大小写和 下划线 都不太好（至少对我来说）
  • （函数，类或任何其他）名称中的“ my ”（或其任何变体）简直是伤脑筋

  • Python 部分：

  • 正如我在评论中所述，必须在 Python中 “复制” C 内容 __

  • 尽管我认为这是一个 主要的 设计缺陷，但为了使问题尽可能接近问题，我只是遵循了它（ GetInterfaceV2 （ V2 部分）考虑到其arg（ 版本 ）没有任何意义）

  • 我个人的观点（尽管没有所有上下文）是（为了确保可伸缩性），该函数应返回通用结构，并带有一个可由客户端应用程序检查的附加字段（例如 version ）。

输出 ：

(py35x64_test)

e:WorkDevStackOverflowq051507196>”c:Installx86MicrosoftVisual Studio
Community2015vcvcvarsall.bat” x64

(py35x64_test) e:WorkDevStackOverflowq051507196>dir /bpre00.pydll00.c(py35x64_test) e:WorkDevStackOverflowq051507196>cl /nologo dll00.c

/link /DLL /OUT:test00.dll
dll00.c
Creating library test00.lib and object test00.exp

(py35x64_test) e:WorkDevStackOverflowq051507196>dir /bpre00.pydll00.cdll00.objtest00.dlltest00.exptest00.lib(py35x64_test)

e:WorkDevStackOverflowq051507196>”e:WorkDevVEnvspy35x64_testscriptspython.exe”
pre00.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32

Testing returned interface: <__main__.LP_DllInterfaceV2 object at

0x00000219984EBAC8>

   NULL pointer returned from CTesting returned interface: <__main__.LP_DllInterfaceV2 object at

0x00000219984EBB48>

        [dll00.c] (16) - [IsValidInt]:  ARG0: -2718281    `is_valid_int` member returned: 2718281        [dll00.c] (22) - [InvalidInt]    `invalid_int` member returned: 0        [dll00.c] (28) - [IsValidSize]:  ARG0: 3141592    `is_valid_size` member returned: -3141592