I take back the first "Yes" answer. Alas, the % operator is a mess, especially for %d/%o/%x. For subclassed longs, it *is* attempting to call the overridden __oct__, and this is causing the SystemError. It looks like this code wasn't really revisited when subclassing int and long was introduced. :-( For subclassed ints, it never looks at the overridden __oct__. For objects that are neither, it attempts to convert them to ints using __int__ first.
The trend in 3.0 is to completely kill __oct__ specialization and rely only on __int__ instead. So maybe I should retract my retraction and claim that '%o' % c(5) should indeed return '5'. The bug stands though. There's a relatively simple fix. --Guido On Nov 14, 2007 11:41 AM, Guido van Rossum <[EMAIL PROTECTED]> wrote: > Yes, and yes. There may be time still to fix the SystemError in 2.5.2! > > > On Nov 14, 2007 11:16 AM, Mike Stall <[EMAIL PROTECTED]> wrote: > > > > > > > > > > This is my first post, so here's a quick intro: I've recently joined the > > IronPython team at Microsoft, after about 6 years as a developer on the the > > .NET runtime (CLR). > > > > I'm currently trying to make IronPython match CPython's behavior regarding > > some % format string to a level of detail not documented by the spec. > > (http://docs.python.org/lib/typesseq-strings.html) > > > > While exploring to determine what CPython's behavior is, I'm hitting a > > SystemError in CPython. > > > > Given the following snippet: > > > > class c(long): > > def __oct__(self): > > return '100' > > > > x=c(5) > > oct(x) # expected to print 100 > > '%o' % x # expected to use print '5' > > > > It looks like in CPython, '%o' uses __int__ and so it should ignore __oct__ > > and print 5. > > > > However, I'm hitting an SystemError in CPython with this snippet: > > > > Python 2.5.1 (r251:54863, Apr 18 2007, 08:51:08) [MSC v.1310 32 bit (Intel)] > > onwin32 > > Type "help", "copyright", "credits" or "license" for more information. > > >>> class c(long): > > ... def __oct__(self): > > ... return '100' > > ... > > >>> x=c(5) > > >>> oct(x) # expected to print 100 > > '100' > > >>> '%o' % x # expected to use print '5' > > Traceback (most recent call last): > > File "<stdin>", line 1, in <module> > > SystemError: \loewis\25\python\Objects\stringobject.c:4236: bad argument to > > internal function > > > > Note that if c derives from 'int' instead of 'long', everything works as > > expected. > > > > 1. Can somebody confirm that '%o' should not use __oct__ and that is uses > > __int__ instead, and that the correct output from ('%o' % x) is indeed 5? > > 2. Should I file a bug for the SystemError exception? > > > > Thanks, > > Mike > > http://blogs.msdn.com/jmstall > > > > > > _______________________________________________ > > 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/guido%40python.org > > > > > > > > -- > --Guido van Rossum (home page: http://www.python.org/~guido/) > -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ 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
