Terry J. Reedy <[email protected]> added the comment:
After more thought and investigation, I have changed my opinions on this issue.
Allowing unicode string for locale in 2.7:
Since the module predates unicode strings (it is in 1.5) and since the locale
string is passed to a C function, 'string' in the doc can just as well be taken
to mean ascii byte string only, as the code requires. As far as I know, unicode
is never needed. Allowing such could be considered a feature addition, which is
not allowed for 2.7. So I would reject the OP's request (and have hence changed
the title).
Expected failure cases could be added to test_locale.py.
Options for locale name:
As I remember, multiple assignments in 1.5, as in
def _build_localename(localetuple):
language, encoding = localetuple
required a tuple on the right and was called 'tuple unpacking'.
Now, any iterable producing 2 items works; Rather than change to code to check
that 'localetuple' really is a tuple (which could break code and the principle
of duck-typing), I think the doc should be updated to
"If locale is specified, it may be a None, a string, or an iterable producing
two strings, language code and encoding."
This is not a feature addition but a recognition of a new feature added
versions ago. The parameter name in the private function should then be
shortened to just 'locale'.
Test cases with non-tuples could be added if not present now.
Exception message:
The current message arises from setlocale assuming that a 'locale' that is
neither None or a string is a valid iterable for a call to _build_localename. A
strings of the wrong type produces too many items and hence the obscure message.
Python is known to be inconsistent in its usage of ValueError versus TypeError
for builtin function args. Guido has said to leave inconsistencies rather than
break code. So I retract the ValueError to TypeError suggestion.
The accompanying messages, however, can be improved. The lines above that fails
could be wrapped with
try:
language, encoding = locale
except ValueError:
raise ValueError("Locale must be None, a string, or an iterable of two
strings -- language code, encoding -- not {}".format(locale))
The scope of the wrapper could be extended to the entire function so that
failure of
return language + '.' + encoding
would also be caught. Failure would happen if locale produced 2 non-strings
items, so that the double assignment 'worked', but the string concatenation
failed.
A complication: the doc says
"exception locale.Error
Exception raised when setlocale() fails.
locale.setlocale(category, locale=None)
...If the modification of the locale fails, the exception Error is raised."
So it seems that either a) the wrapper above should raise Error instead, or the
doc could more clearly say "Exception raised when the locale passed to
setlocale is not recognized."
----------
nosy: +lemburg, loewis
title: setlocale fails with unicode strings on Py2 and with byte strings on Py3
-> setlocale error message is confusing
versions: +Python 3.3 -Python 3.1
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