At 07:24 PM 9/26/2007 +0400, Oleg Broytmann wrote: >Hello! > > (This seems like a "developing with Python" question and partially it is >but please read on.) > > I have a class that represents SQL queries. Instances of the class can >be iterated over. As an SQL query doesn't know in advance if it will >produce any row the class doesn't implement __len__(). Moreover, users of >the class sometimes write > >if sqlQuery: > for row in sqlQuery: ... >else: > # no rows
This isn't consistent with iterators; e.g.: >>> x=iter([]) >>> if x: print "yes" ... yes ISTM that you should be returning "True" from __nonzero__, since you don't implement len(). >1. Should I consider this a bug in the logging module (and other libraries) > and submit patches? >2. Or should I stop raising exceptions in __nonzero__()? #2 - Python objects should always be __nonzero__, unless they are empty containers, zeros, or otherwise specifically False. It's reasonable for libraries to expect that truth-testing an object is always safe. _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
