将函数指针作为python中的参数传递时出错

Question

Note: dll written in C++ and accessing in python

import ctypes
import os
from ctypes import*

def plateDetectedCallback(hEngine, hPlate):
    print "successfully loaded"
    pass

lib = cdll.LoadLibrary("some dll path")
hLPRRarams = lib.LPRParams_Create()
hEngine = lib.LPREngine_Create(hLPRRarams, True,plateDetectedCallback) # error in this line

1. plateDetectedCallback is a callback function or function pointer

2. Now I want to call callback function as per documentation like plateDetectedCallback(LPRENGINE hEngine, LPRPLATE hPlate)

I tried in different ways to call the callback function but failed. please, Can any one help in this. Thankyou

I am getting the exception like:

NameError: name 'plateDetectedCallback' is not defined

Answer 1

I solved the Issue Using @CFUNCTYPE decorator

@c.CFUNCTYPE(None, c_void_p, c_void_p)
    def plateDetectedCallback(hEngine, hPlate):
        .....
        .....

None is the return type of dll(ie void), c_void_p is a void pointer

make sure to import the ctypes