Writing Python ctypes for Function pointer callback function in C -

i trying write python code call dll functions , stuck @ function below, believe related typedef callback function or function pointer thing.

i have tested code below, when callback function called, python crashes (window notification-- python.exe has stop responding) no debug msg.

i confused, appreciated :)

thanks!

c:

#ifdef o_win32 /** @cond */ #ifdef p_exports #define api __declspec(dllexport) #else #define api __declspec(dllimport) #endif // #ifdef p_exports /** @endcond */ #endif // #ifdef o_win32  // type definition typedef void (__stdcall *statuscb)(int nerrorcode, int nsid, void *parg);  //function  void getstatus(statuscb statusfn, void *parg); 

python:

from ctypes import *  def statuscb(nerrorcode, nsid, parg):     print 'hello world'  def start():     lib = cdll.loadlibrary('api.dll')     cmpfunc = winfunctype(c_int, c_int, c_void_p)     cmp_func = cmpfunc(statuscb)     status_func = lib.getstatus     status_func(cmp_func) 

your callback type has wrong signature; forgot result type. it's getting garbage collected when function exits; need make global.

your getstatus call missing argument parg. plus when working pointers need define argtypes, else you'll have problems on 64-bit platforms. ctypes' default argument type c int.

from ctypes import *   api = cdll('api.dll') statuscb = winfunctype(none, c_int, c_int, c_void_p)  getstatus = api.getstatus getstatus.argtypes = [statuscb, c_void_p] getstatus.restype = none  def status_fn(nerrorcode, nsid, parg):             print 'hello world'     print parg[0]  # 42?  # reference callback keep alive _status_fn = statuscb(status_fn)  arg = c_int(42) # passed callback?      def start():             getstatus(_status_fn, byref(arg))