Ezio Melotti <ezio.melo...@gmail.com> added the comment: Indeed this behavior doesn't seem to be documented.
When the string is unicode and the fillchar non-unicode Python implicitly tries to decode the fillchar (and possibly it raises a TypeError if it's not in range(0,128)): >>> u'x'.center(5, 'y') # unicode string, non-unicode (str) fillchar u'yyxyy' # the fillchar is decoded When the string is non-unicode it only accepts a non-unicode fillchar (e.g. 'x'.center(5, 'y')) and it raises a TypeError if the fillchar is unicode: >>> 'x'.center(5, u'y') # non-unicode (str) string, unicode fillchar Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: center() argument 2 must be char, not unicode If it tries to decode the fillchar when the string is unicode, it could also try to encode the unicode fillchar (and possibly raise a TypeError) when the string is non-unicode. Py3, instead, seems to have the opposite behavior. It implicitly encodes unicode fillchars into byte strings when the string is a byte string but it doesn't decode a byte fillchar if the string is unicode: >>> b'x'.center(5, 'y') # byte string, unicode fillchar b'yyxyy' # the fillchar is encoded >>> 'x'.center(5, b'y') # unicode string, byte fillchar Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: The fill character cannot be converted to Unicode In the doc [1] there's written that "The methods on bytes and bytearray objects don’t accept strings as their arguments, just as the methods on strings don’t accept bytes as their arguments." so b'x'.center(5, 'y') should probably raise an error on Py3 (I could open a new issue for this). [1]: http://docs.python.org/3.0/library/stdtypes.html#bytes-and-byte-array-methods - In the note ---------- nosy: +ezio.melotti versions: +Python 2.6, Python 3.0 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue3446> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
