On Feb 26, 9:41 am, "Diez B. Roggisch" <de...@nospam.web.de> wrote: > Am 26.02.10 16:32, schrieb darnzen: > > > > > > > On Feb 26, 3:15 am, "Diez B. Roggisch"<de...@nospam.web.de> wrote: > >> Am 26.02.10 06:07, schrieb darnzen: > > >>> Having an odd problem that I solved, but wondering if its the best > >>> solution (seems like a bit of a hack). > > >>> First off, I'm using an external DLL that requires static callbacks, > >>> but because of this, I'm losing instance info. It could be import > >>> related? It will make more sense after I diagram it: > > >>> #Module main.py > >>> from A import * > > >>> class App: > >>> def sperg(self): > >>> self.a = A() > > >>> app = App() > >>> [main loop and such] > >>> ----------------------------- > >>> # Module A.py > >>> import main > >>> class Foo: > >>> Selves=[] > >>> def __init__(self): > >>> Foo.Selves.append(self) > >>> �...@staticmethod > >>> def chum_callback(nType, nP): > >>> # Need to access function / data in app instance > >>> app.sperg(nP) > >>> # Need to access func data in Foo > >>> # I'm pulling 'self' ouf of list made in constructor > >>> self = Foo.getSelf(nP) > > >>> def getSelf(nP): > >>> return self.Selves[nP] > > >>> --------------------------------------------------------------------- > >>> So basically I added a list of instances to the base class so I can > >>> get at them from the staticmethod. > >>> What's bothering me the most is I can't use the global app instance in > >>> the A.py module. > > >>> How can I get at the app instance (currently I'm storing that along > >>> with the class instance in the constructor)? > >>> Is there another way to do this that's not such a hack? > > >>> Sorry for the double / partial post :( > > >> Can you show how you pass the staticmethod to the C-function? Is the DLL > >> utilized by ctypes? > > >> I don't see any reason you couldn't use a bound method, which would give > >> you your self, instead relying on global state. > > >> Diez > > > __main__.K<< *facepalm* should of tried that! > > > Yeah I'm using ctypes. The DLL callback set ups are as follows. The > > local callback is in the App namespace (in this case, some callbacks > > are in different modules as noted in OP), but still no access to self: > > > #Function wrapper > > A.expCallback = WINFUNCTYPE(None, c_int, c_int, \ > > POINTER(Data_s))(A.Callback) > > > #DLL call to register the local callback function > > DLLSetCallback(self.hID, A.SubID, EVENTID, A.expCallback) > > > class A: > > #Local callback function > > �...@staticmethod > > def Callback(hID, SubID, Data): > > print 'I DON'T KNOW WHO I AM OR WHERE I CAME FROM!!' > > print 'BUT WITH hID, and SubID, I CAN FIGURE IT OUT' > > print 'IF I STORE A REFERENCE TO MYSELF IN A DICT' > > print 'USING KEY GENERATED FROM hID, SubID' > > pass > > > I'm not sure why they need to be static callbacks, but the DLL doc's > > say "when using object based languages, such as c++, callback > > functions must be declared as static functions and not instance > > methods", and I couldn't get it to work without setting it up that > > way. I could probably have them all be "classless" functions, but with > > 100's of these, my namespace would be polluted up the wazoo, and I'd > > still have the problem that they wouldn't have access to instance > > methods / properties. > > The above code can't work with self, because you use > > A.expCallback > > which at best can of course be a classmethod. > > You need to instead invoke DLLSetCallback with a bound method, like this > > a = A() > DLLSetCallback(self.hID, A.SubID, EVENTID, a.expCallback) > > Also, the DLL-docs seem to refer to *C* or *C++*, where the concept of > static functions is differently. If ctypes manages to get *some* > callback passed, I'm 100% positive that it can pass *any* callable you > like, including bound methods. > > Diez
This was originally how my code was set up, invoking with the bound methods, but it didn't work (crashing and bizzaro errors) and I was pulling my hair out. Then I read the documentation and changed it to static methods and everything started working. Believe me, I totally understand how using bound methods would make this problem go away. -- http://mail.python.org/mailman/listinfo/python-list
