This is expected behavior (see http://www.python.org/doc/essays/cleanup) but it is definitely a wart of Python. The best advice I can give you is *never* use __del__. There are alternatives, such as the with statement, weak references or atexit. See for instance http://code.activestate.com/recipes/523007/ If you Google in this newsgroup for __del__ you will find a lot of discussion.
Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
