I had a discussion regarding the use of python integers some time ago with Daniel Krenn.
Basically, range and xrange produce Python integers, whereas srange and sxrange (from sage.misc.misc) produce Integers. Also, when dealing with lists, len usually produces Python int's. (Maybe Daniel has some more common pitfalls?) In any case, after trying to change all range and xrange to srange and sxrange in dyck_word.py, the error still occurred. It seems that directly after building sage, something happens such that the parameters 4,2 in the doctest sage: TestSuite(DyckWords(4,2)).run() are being treated as Python integers, rather than sage integers. Then, when the TestSuite comes to the test where it checks that cardinality actually returns an Integer, it fails because the Python int's 4 and 2 cause the cardinality to be a Python int, too. Vincent has cured the symptom of these mysteriously occurring int's in http://trac.sagemath.org/ticket/18244 -- but the nature of the original problem (i.e. that there are Python int's in the first place only with ./sage -bt and *not* with ./sage -t -- and this also not on all platforms) suggests that this might be something that runs deep. Am Samstag, 18. April 2015 05:54:29 UTC+2 schrieb Darij Grinberg: > > This stuff is spooky... I've always been treating int and Integer as > interchangeable when coding for Sage. Maybe I've introduced several such > bugs. > > Can anyone explain in a noob-friendly way how an implementer should decide > between returning ints and Integers, when it is OK to treat them as > equivalent, and in what cases an explicit conversion into Integer needs to > be made? Thanks a lot! > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
