Datetime.strptime error in wxPython why

[wstates]

# coding=utf-8
import wx
import sys
import datetime

if __name__ == "__main__":
    print("wxpython version:", wx.version())
    print("Python version:", sys.version)
    print("Run before wx:", datetime.datetime.strptime("02/02/2020", '%d/%m/%Y'), "normal")
    app = wx.App()
    print("Run after wx:", datetime.datetime.strptime("02/02/2020", '%d/%m/%Y'), "error")

    # frame = MainFrame()
    # frame.SetSize(0, 0, 1200, 750)
    # frame.Center()
    # frame.Show()
    app.MainLoop()

wxpython version: 4.1.0 msw (phoenix) wxWidgets 3.1.4
Python version: 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)]
Run before wx: 2020-02-02 00:00:00 normal
Traceback (most recent call last):
  File "K:/test/a.py", line 14, in <module>
    print("Run after wx:", datetime.datetime.strptime("02/02/2020", '%d/%m/%Y'), "error")
  File "C:\Program Files\Python36\lib\_strptime.py", line 565, in _strptime_datetime
    tt, fraction = _strptime(data_string, format)
  File "C:\Program Files\Python36\lib\_strptime.py", line 334, in _strptime
    if (_getlang() != locale_time.lang or
  File "C:\Program Files\Python36\lib\_strptime.py", line 31, in _getlang
    return locale.getlocale(locale.LC_TIME)
  File "C:\Program Files\Python36\lib\locale.py", line 581, in getlocale
    return _parse_localename(localename)
  File "C:\Program Files\Python36\lib\locale.py", line 490, in _parse_localename
    raise ValueError('unknown locale: %s' % localename)
ValueError: unknown locale: zh-CN

[cwassert]

See also pyinstaller/pyinstaller#4874

[AndersMunch]

I'm seeing this too with wxPython 4.1.0 (and Python 3.8.1 MSW 64 bit, for the record).
The same traceback occurs even if the locale is set explicitly through wx:

import wx
import datetime
app = wx.App()
loc = wx.Locale(wx.LANGUAGE_ENGLISH_UK)
print(datetime.datetime.strptime('2020', "%Y"))

However, if the locale is set using the Python locale module, it doesn't:

import wx
import datetime, locale
app = wx.App()
locale.setlocale(locale.LC_ALL, 'en_GB')
print(datetime.datetime.strptime('2020', "%Y"))

No traceback in this case. It seems to be a usable workaround.

Note that some older 4.0.x wxPython's insisted on the opposite, requiring wx.Locale instead of Python locale, as seen in this assertion failure from 4.0.4 wx.Image.ConvertToBitmap:
wx._core.wxAssertionError: C++ assertion "strcmp(setlocale(LC_ALL, NULL), "C") == 0" failed at ..\..\src\common\intl.cpp(1579) in wxLocale::GetInfo(): You probably called setlocale() directly instead of using wxLocale and now there is a mismatch between C/C++ and Windows locale.

Edited to add:
Apparently not just older wxPythons: 4.1.0 wx.Image gave me this:

wx._core.wxAssertionError: C++ assertion "wxString::Format("%.3f", 1.23).find(str) != wxString::npos" failed at ..\..\src\common\intl.cpp(1638) in `anonymous-namespace'::GetInfoFromLCID(): Decimal separator mismatch -- did you use setlocale()?If so, use wxLocale to change the locale instead.

It seems locale.setlocale is not a usable workaround after all.

[swt2c]

For those seeing this, what does locale.getlocale() return before and after calling wx.App()?

[wstates]

对于那些看到此消息的人，在_致电_之前_和_之后locale.getlocale()返回什么？____wx.App()

# coding=utf-8

import wx
import sys
import datetime, locale

if __name__ == "__main__":
    print("wxpython version:", wx.version())
    print("Python version:", sys.version)
    print("Run before wx:", locale.getlocale())
    app = wx.App()
    print("Run after wx:", locale.getlocale())
    

    # Use this locale.setlocale(locale.LC_ALL, "") to return to normal.
    locale.setlocale(locale.LC_ALL, "") 
    print("Run after wx:", locale.getlocale())

    app.MainLoop()

wxpython version: 4.1.0 msw (phoenix) wxWidgets 3.1.4
Python version: 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)]
Run before wx: (None, None)
Traceback (most recent call last):
  File "K:/test/a.py", line 14, in <module>
    print("Run after wx:", locale.getlocale())
  File "C:\Program Files\Python36\lib\locale.py", line 581, in getlocale
    return _parse_localename(localename)
  File "C:\Program Files\Python36\lib\locale.py", line 490, in _parse_localename
    raise ValueError('unknown locale: %s' % localename)
ValueError: unknown locale: zh-CN

    def InitLocale(self):
        """
        Try to ensure that the C and Python locale is in sync with wxWidgets locale.
        """
        import locale
        print("BugTest1", locale.getlocale())

        self.ResetLocale()
        print("BugTest2", locale.getlocale())

        import locale
        print("BugTest3", locale.getlocale())

        try:
            loc, enc = locale.getlocale()
        except ValueError:
            loc = enc = None
            print("BugTest4", locale.getlocale())
        print("BugTest5", locale.getlocale())

        # Try to set it to the same language as what is already set in the C locale
        info = wx.Locale.FindLanguageInfo(loc) if loc else None
        if info:
            self._initial_locale = wx.Locale(info.Language)
            print("BugTest6", locale.getlocale())

        else:
            # otherwise fall back to the system default
            print("BugTest7", locale.getlocale())
            self._initial_locale = wx.Locale(wx.LANGUAGE_DEFAULT)
            print("BugTest8", locale.getlocale())

wxpython version: 4.1.0 msw (phoenix) wxWidgets 3.1.4
Python version: 3.6.8 (tags/v3.6.8:3c6b436a57, Dec 24 2018, 00:16:47) [MSC v.1916 64 bit (AMD64)]
Run before wx: (None, None)
BugTest1 (None, None)
BugTest2 (None, None)
BugTest3 (None, None)
BugTest5 (None, None)
BugTest7 (None, None)
Traceback (most recent call last):
  File "i:\python\lib\site-packages\wx\core.py", line 2204, in OnPreInit
    self.InitLocale()
  File "i:\python\lib\site-packages\wx\core.py", line 2287, in InitLocale
    print("BugTest8", locale.getlocale())
  File "C:\Program Files\Python36\lib\locale.py", line 581, in getlocale
    return _parse_localename(localename)
  File "C:\Program Files\Python36\lib\locale.py", line 490, in _parse_localename
    raise ValueError('unknown locale: %s' % localename)
ValueError: unknown locale: zh-CN

[wstates]

self._initial_locale = wx.Locale(wx.LANGUAGE_DEFAULT)
changed to

self._initial_locale = wx.Locale(wx.LANGUAGE_UNKNOWN)
No traceback in this case

[swt2c]

@RobinD42 perhaps in the case where Python's locale.getlocale() returns None, wxPython should NOT be calling wx.Locale(wx.LANGUAGE_DEFAULT)? It seems like in that case you are setting a locale where none is currently set.

[AndersMunch]

For those seeing this, what does locale.getlocale() return before and after calling wx.App()?

Python 3.8.1 (tags/v3.8.1:1b293b6, Dec 18 2019, 23:11:46) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import locale
>>> locale.getlocale()
('Danish_Denmark', '1252')
>>> import wx
>>> wx.version()
'4.1.0 msw (phoenix) wxWidgets 3.1.4'
>>> locale.getlocale()
('Danish_Denmark', '1252')
>>> app = wx.App()
>>> locale.getlocale()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\flonidan\env\Python38-64\lib\locale.py", line 591, in getlocale
    return _parse_localename(localename)
  File "C:\flonidan\env\Python38-64\lib\locale.py", line 499, in _parse_localename
    raise ValueError('unknown locale: %s' % localename)
ValueError: unknown locale: da-DK

[cwassert]

What confuses me about the error message is the hyphen. Because the usual notation uses an underscore.

>>> locale.setlocale(locale.LC_ALL, ('en-US', 'UTF-8'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.8/locale.py", line 608, in setlocale
    return _setlocale(category, locale)
locale.Error: unsupported locale setting
>>> locale.setlocale(locale.LC_ALL, ('en_US', 'UTF-8'))
'en_US.UTF-8'
>>> 

See also locale.locale_alias.keys().

[swt2c]

There will be a new version of InitLocale() in wxPython 4.1.1. Can you try the snapshot builds and see if this issue is resolved with one of the latest snapshots? https://wxpython.org/Phoenix/snapshot-builds/

[AndersMunch]

4.1.1a1 is an improvement, so long as you stick with default locale everything seems fine:

Python 3.8.3 (tags/v3.8.3:6f8c832, May 13 2020, 22:37:02) [MSC v.1924 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import locale
>>> locale.getlocale()
('Danish_Denmark', '1252')
>>> import wx
>>> wx.version()
'4.1.1a1.dev4861+961dda67 msw (phoenix) wxWidgets 3.1.4'
>>> locale.getlocale()
('Danish_Denmark', '1252')
>>> app = wx.App()
>>> locale.getlocale()
('da_DK', 'ISO8859-1')

But setting a different locale does not work:

Python 3.8.3 (tags/v3.8.3:6f8c832, May 13 2020, 22:37:02) [MSC v.1924 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import wx
>>> app = wx.App()
>>> loc = wx.Locale(wx.LANGUAGE_ENGLISH_UK)
>>> import locale
>>> locale.getlocale()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\flonidan\env\Python38-64\lib\locale.py", line 591, in getlocale
    return _parse_localename(localename)
  File "C:\flonidan\env\Python38-64\lib\locale.py", line 499, in _parse_localename
    raise ValueError('unknown locale: %s' % localename)
ValueError: unknown locale: en-GB

[AndersMunch]

Update: wxPython 4.1.1/wxWidgets 3.1.5 is out, and it works exactly like 4.1.1a1. It's a showstopper, so I remain stuck on 4.0.7/3.0.5.

[RobinD42]

This issue has been mentioned on Discuss wxPython. There might be relevant details there:

https://discuss.wxpython.org/t/wxpython4-1-1-python3-8-locale-wxassertionerror/35168/2

[RobinD42]

For those still having issues with this and are using non-US locales, please try this experiment. The root of the problem started when Python 3.8+ on Windows started changing the locale to something other than the default unset value, so perhaps the simplest thing that can be done is to just change it back to "C" instead of overdoing things to try and bring the C runtime and wxWIdgets into sync with what the system thinks should be the default.

So try adding the following method to your wx.App-derived class.

    def InitLocale(self):
        import sys
        if sys.platform.startswith('win') and sys.version_info > (3,8):
            import locale
            locale.setlocale(locale.LC_ALL, "C")

If you also need to set an explicit wx.Locale then do so after the code above, and remember to hold on to the reference to the wx.Local object.

Please reply with how it works for you, and if it doesn't help then also reply with any clues you may have discovered.

[AndersMunch]

Tried the InitLocale override, and yes, it works to set the "C" locale. You can't subsequently set a different locale; any other locale than the C locale (specifically, wx.LANGUAGE_ENGLISH) or the default locale results in this error message from wx.Locale:

wx._core.wxAssertionError: C++ assertion ""!szLocale.empty()"" failed at ..\..\src\common\intl.cpp(304) in wxLocale::Init(): no locale to set in wxLocale::Init()