New submission from Chris Jerdonek: format(value) and value.__format__() behave differently even though the documentation says otherwise: "Note: format(value, format_spec) merely calls value.__format__(format_spec)." (from http://docs.python.org/library/functions.html?#format ) The difference happens when the format string is unicode. For example:
format(10, u'n') u'10' (10).__format__(u'n') # parentheses needed to prevent SyntaxError '10'
So either the documentation should be changed, or the behavior should be changed to match.
Related to this: neither the "Format Specification Mini-Language" documentation nor the string.Formatter docs seem to say anything about the effect that a unicode format string should have on the return value (in particular, should it cause the return value to be unicode or not):
http://docs.python.org/library/string.html#formatspec
http://docs.python.org/library/string.html#string-formatting
See also issue 15276 (int formatting), issue 15951 (empty format string), and issue 7300 (unicode arguments).
----------
assignee: docs@python
components: Documentation
messages: 170575
nosy: cjerdonek, docs@python
priority: normal
severity: normal
status: open
title: format(value) and value.__format__() behave differently with unicode format
type: behavior
versions: Python 2.7
_______________________________________
Python tracker