Antoine Pitrou <pit...@free.fr> added the comment: Here is the reason. Starting from Python 2.6, classes can redefine subclass checking using a special method named __subclasscheck__. Since this method can contain arbitrary code, we have to guard against recursion when calling it. Therefore, the recursion count is incremented before doing a subclass checking.
Now the problem is that when checking for an exception, we do exactly that: check whether the raised exception is a subclass of a given type. If the raised exception occurred just after a recursion overflow, it can happen that subclass checking overflows the recursion count again. However, since we don't want the newly raised exception (during exception subclass checking) to overwrite the original one, so we just write out it (using PyErr_WriteUnraisable, precisely) and then discard it. That's where these strange messages come from. (note: py3k has a slightly different recursion checking mechanism and doesn't print such messages) ---------- nosy: +amaury.forgeotdarc, loewis, pitrou _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue5508> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
