Re: [comtypes-users] __del__ called more than once on a comtypes COM POINTER object
James Teh schrieb: Hi Thomas, In NVDA, we sometimes see access violation and vtable errors in __del__ on comtypes COM POINTER objects and intermittant crashes. I eventually figured that this might relate to Release() being called too many times. I then discovered that __del__ on these objects is sometimes called more than once. (We never call __del__ ourselves, so this is happening elsewhere.) As I understand it, Python should only ever call it once. Well, __del__ could revive the object, but comtypes doesn't do this afaik. I discovered this using the following rather nasty monkey patch before any COM objects are used: from comtypes import _compointer_base _cpbDel = _compointer_base.__del__ def newCpbDel(self): assert not hasattr(self, _deleted), compointer already deleted _cpbDel(self) self._deleted = True newCpbDel.__name__ = __del__ _compointer_base.__del__ = newCpbDel del _compointer_base This assertion does get raised. While I have come up with an exact set of steps to reproduce with NVDA and Firefox, I haven't yet managed to narrow it down to a programmatic test case due to the sheer number of interactions and code paths. I can tell you that we use QueryInterface quite a bit if that helps in any way. Can you think of any reason this might be happening? Is there any code in the ctypes POINTER type that calls __del__? No, and no. It would be great if you can provide some code that has this problem. -- Thanks, Thomas -- Come build with us! The BlackBerryreg; Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9#45;12, 2009. Register now#33; http://p.sf.net/sfu/devconf ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
[comtypes-users] __del__ called more than once on a comtypes COM POINTER object
Hi Thomas, In NVDA, we sometimes see access violation and vtable errors in __del__ on comtypes COM POINTER objects and intermittant crashes. I eventually figured that this might relate to Release() being called too many times. I then discovered that __del__ on these objects is sometimes called more than once. (We never call __del__ ourselves, so this is happening elsewhere.) As I understand it, Python should only ever call it once. I discovered this using the following rather nasty monkey patch before any COM objects are used: from comtypes import _compointer_base _cpbDel = _compointer_base.__del__ def newCpbDel(self): assert not hasattr(self, _deleted), compointer already deleted _cpbDel(self) self._deleted = True newCpbDel.__name__ = __del__ _compointer_base.__del__ = newCpbDel del _compointer_base This assertion does get raised. While I have come up with an exact set of steps to reproduce with NVDA and Firefox, I haven't yet managed to narrow it down to a programmatic test case due to the sheer number of interactions and code paths. I can tell you that we use QueryInterface quite a bit if that helps in any way. Can you think of any reason this might be happening? Is there any code in the ctypes POINTER type that calls __del__? Thanks. Jamie -- James Teh Email/MSN Messenger/Jabber: ja...@jantrid.net Web site: http://www.jantrid.net/ -- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
