Python ctypes 函数原型参数处理详解

import ctypes
import ctypes.wintypes

# 定义WLAN_NOTIFICATION_DATA和WLAN_NOTIFICATION_CALLBACK类型
PWLAN_NOTIFICATION_DATA = ctypes.c_void_p
WLAN_NOTIFICATION_CALLBACK = ctypes.WINFUNCTYPE(None, PWLAN_NOTIFICATION_DATA, ctypes.wintypes.LPVOID)

# 创建一个空的（null）回调函数实例作为默认值
null_callback = WLAN_NOTIFICATION_CALLBACK()

# 定义一个有效的回调函数（用于测试）
@WLAN_NOTIFICATION_CALLBACK
def callback(param1, param2):
    print(f"Callback received: {param1}, {param2}")

# 定义参数标志
IN = 1
OUT = 2
DEFAULT_ZERO = 4

# 加载wlanapi库
wlanapi = ctypes.WinDLL('wlanapi')

# 定义WlanRegisterNotification的函数原型
proto = ctypes.WINFUNCTYPE(
    ctypes.wintypes.DWORD, # 返回类型
    ctypes.wintypes.HANDLE,
    ctypes.wintypes.DWORD,
    ctypes.wintypes.BOOL,
    WLAN_NOTIFICATION_CALLBACK,
    ctypes.wintypes.LPVOID,
    ctypes.wintypes.LPVOID,
    ctypes.POINTER(ctypes.wintypes.DWORD),
)

# 绑定函数并指定参数细节
fun = proto(
    ('WlanRegisterNotification', wlanapi),
    (
        (IN, 'hClientHandle'),
        (IN, 'dwNotifSource'),
        (IN, 'bIgnoreDuplicate'),
        # funcCallback和pCallbackContext需要显式默认值，且可以被覆盖
        (IN, 'funcCallback', null_callback), # 使用null_callback作为默认值
        (IN, 'pCallbackContext', None),      # 使用None作为默认值
        # pReserved使用DEFAULT_ZERO，表示该参数不应由Python显式传入
        (IN | DEFAULT_ZERO, 'pReserved'),
        (OUT, 'pdwPrevNotifSource'),
    ),
)

# 设置错误检查函数，以便返回prevNotifSource的值
fun.errcheck = lambda result, func, args: (result, args[5])

# 各种调用方式的测试
print("--- 测试不同参数组合 ---")
print(f"调用 fun(0,0,0): {fun(0,0,0)}") # funcCallback, pCallbackContext, pReserved使用默认值
print(f"调用 fun(0,0,0,callback): {fun(0,0,0,callback)}") # 显式传入callback
print(f"调用 fun(0,0,0,callback,None): {fun(0,0,0,callback,None)}") # 显式传入callback和None
# 以下调用会失败，因为pReserved被标记为DEFAULT_ZERO，不应显式传入
try:
    print(f"尝试调用 fun(0,0,0,callback,None,None): {fun(0,0,0,callback,None,None)}")
except TypeError as e:
    print(f"错误: {e}")

--- 测试不同参数组合 ---
调用 fun(0,0,0): (87, 0)
调用 fun(0,0,0,callback): (87, 0)
调用 fun(0,0,0,callback,None): (87, 0)
错误: call takes exactly 5 arguments (6 given)

import ctypes as ct
import ctypes.wintypes as w

# 定义WLAN_NOTIFICATION_DATA和WLAN_NOTIFICATION_CALLBACK类型
PWLAN_NOTIFICATION_DATA = ct.c_void_p
WLAN_NOTIFICATION_CALLBACK = ct.WINFUNCTYPE(None, PWLAN_NOTIFICATION_DATA, w.LPVOID)

# 创建一个空的（null）回调函数实例作为默认值
null_callback = WLAN_NOTIFICATION_CALLBACK()

# 定义一个有效的回调函数（用于测试）
@WLAN_NOTIFICATION_CALLBACK
def callback(param1, param2):
    print(f"Callback received: {param1}, {param2}")

# 加载wlanapi库
wlanapi = ct.WinDLL('wlanapi')

# 使用.argtypes和.restype直接声明C函数的签名
wlanapi.WlanRegisterNotification.argtypes = (
    w.HANDLE,
    w.DWORD,
    w.BOOL,
    WLAN_NOTIFICATION_CALLBACK,
    w.LPVOID,
    w.LPVOID, # pReserved 在这里被声明为LPVOID类型
    ct.POINTER(w.DWORD)
)
wlanapi.WlanRegisterNotification.restype = w.DWORD

# 编写Python包装函数
def fun(hClientHandle, dwNotifSource, bIgnoreDuplicate,
        funcCallback=null_callback, pCallbackContext=None):
    """
    WlanRegisterNotification的Python包装函数。
    hClientHandle: 客户端句柄
    dwNotifSource: 通知源
    bIgnoreDuplicate: 是否忽略重复通知
    funcCallback: 通知回调函数 (默认null_callback)
    pCallbackContext: 回调上下文 (默认None)
    """
    prevNotifSource = w.DWORD()
    # pReserved 在这里固定传入None，由C函数内部处理为0
    # ct.byref(prevNotifSource) 用于传递指针
    result = wlanapi.WlanRegisterNotification(
        hClientHandle,
        dwNotifSource,
        bIgnoreDuplicate,
        funcCallback,
        pCallbackContext,
        None, # pReserved 始终传入None，因为C函数期望它为0或空
        ct.byref(prevNotifSource)
    )
    return result, prevNotifSource.value

# 各种调用方式的测试
print("\n--- 测试使用argtypes和包装函数 ---")
print(f"调用 fun(0,0,0): {fun(0,0,0)}")
print(f"调用 fun(0,0,0,callback): {fun(0,0,0,callback)}")
print(f"调用 fun(0,0,0,callback,None): {fun(0,0,0,callback,None)}")
# 尝试传入额外的参数，Python函数会直接报错，更符合预期
try:
    print(f"尝试调用 fun(0,0,0,callback,None,None): {fun(0,0,0,callback,None,None)}")
except TypeError as e:
    print(f"错误: {e}")

--- 测试使用argtypes和包装函数 ---
调用 fun(0,0,0): (87, 0)
调用 fun(0,0,0,callback): (87, 0)
调用 fun(0,0,0,callback,None): (87, 0)
错误: fun() takes from 3 to 5 positional arguments but 6 were given