[Python-Dev] sequence slice that wraps, bug or intention?
Hi! I just stumbled across something in Python 2.6 where I'm not sure if it is by design or a fault: x = 'abdc' x[-3:-3] - '' x[-3:-2] - 'b' x[-3:-1] - 'bc' x[-3: 0] - '' The one that actually bothers me here is the last one, I would have expected it to yield 'bcd' instead, because otherwise I don't see a way to specify a slice that starts with a negative index but still includes the last element. Similarly, I would expect x[-1,1] to yield 'ca' or at least raise an error, but not to return an empty string. Bug? Uli -- Sator Laser GmbH Geschäftsführer: Thorsten Föcking, Amtsgericht Hamburg HR B62 932 ** Sator Laser GmbH, Fangdieckstraße 75a, 22547 Hamburg, Deutschland Geschäftsführer: Thorsten Föcking, Amtsgericht Hamburg HR B62 932 ** Visit our website at http://www.satorlaser.de/ ** Diese E-Mail einschließlich sämtlicher Anhänge ist nur für den Adressaten bestimmt und kann vertrauliche Informationen enthalten. Bitte benachrichtigen Sie den Absender umgehend, falls Sie nicht der beabsichtigte Empfänger sein sollten. Die E-Mail ist in diesem Fall zu löschen und darf weder gelesen, weitergeleitet, veröffentlicht oder anderweitig benutzt werden. E-Mails können durch Dritte gelesen werden und Viren sowie nichtautorisierte Änderungen enthalten. Sator Laser GmbH ist für diese Folgen nicht verantwortlich. ** ___ 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
Re: [Python-Dev] sequence slice that wraps, bug or intention?
2009/4/3 Ulrich Eckhardt eckha...@satorlaser.com: Hi! I just stumbled across something in Python 2.6 where I'm not sure if it is by design or a fault: x = 'abdc' x[-3:-3] - '' x[-3:-2] - 'b' x[-3:-1] - 'bc' x[-3: 0] - '' The one that actually bothers me here is the last one, I would have expected it to yield 'bcd' instead, because otherwise I don't see a way to specify a slice that starts with a negative index but still includes the last element. Similarly, I would expect x[-1,1] to yield 'ca' or at least raise an error, but not to return an empty string. Bug? Feature. Documented behaviour, even (http://docs.python.org/reference/expressions.html#id5 section Slicings). This question is more appropriate for python-list (comp.lang.python) as it is about using Python, rather than the development of the Python interpreter itself (although I can see that your uncertainty as to whether this was a bug might have led you to think this was a more appropriate list). You should first confirm on python-list that a given behaviour is a bug, and if it is, post it to the tracker, rather than to python-dev. In this case, the behaviour is fine. As regards your point I don't see a way to specify a slice that starts with a negative index but still includes the last element what you want is x[-3:]. If you want to discuss this further, please do so on python-list. Paul. ___ 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
