[英]python ctypes callback c++
C ++接口: unsigned long _stdcall NAPI_JsonCommand(char * szCommand,unsigned long * pulRet,char * pBuf,int nLen,unsigned long * pulDevCode);
回調函數定義: typedef long(_stdcall fMsgCallback)(int nMsg,void pUserData,char * pBuf,int nLen,int nParam);
python(3.5.2)代碼
#coding=utf-8
__author__ = 'wjyang'
import ctypes
from ctypes import *
import json
dll = ctypes.WinDLL("napi.dll")
CMPFUNC=WINFUNCTYPE(c_long,c_int,c_void_p,c_char_p,c_int,c_int)
def py_cmp_func(nMsg,pUserData,pBuf,nLen,nParam):
print("this is callback")
return 1
addr=hex(id(CMPFUNC(py_cmp_func)))
dict={"KEY":"CONNECTREGISTER","PARAM":{"CALLBACK":addr,"AUTOPIC":0,"IP":"192.168.150.30","PORT":5556}}
dicts=json.dumps(dict)
commd=c_char_p(dicts.encode())
print(dll.NAPI_JsonCommand(commd,c_int(0),None,c_int(0),None))
,
結果是未執行回調函數py_cmp_func
如果使用
dict={"KEY":"CONNECTREGISTER","PARAM":{"CALLBACK":CMPFUNC(py_cmp_func),"AUTOPIC":0,"IP":"192.168.150.30","PORT":5556}}
dicts=json.dumps(dict)
會錯的! TypeError:位於0x021BB8A0的WinFunctionType對象不是JSON可序列化的
在json字符串中有回調函數,該回調函數的內存地址如何傳遞給c ++?
不確定是否可以,但是我看到兩個問題:
addr=hex(id(CMPFUNC(py_cmp_func)))
在上一行中,執行該行后會銷毀CMPFUNC(py_cmp_func)
,因為將不再有引用。 同樣, id()
給出CMPFUNC
對象的地址,而不是內部函數指針。 嘗試以下任一方法:
callback = CMPFUNC(py_cmp_func) # keep a reference
addr = addressof(callback) # Not sure you need hex...
或使用裝飾器,該裝飾器也將保留對該函數的引用:
@WINFUNCTYPE(c_long,c_int,c_void_p,c_char_p,c_int,c_int)
def py_cmp_func(nMsg,pUserData,pBuf,nLen,nParam):
print("this is callback")
return 1
addr = addressof(py_cmp_func) # Again, not sure about hex.
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