STINNER Victor added the comment: My experience with changing the Python "filesystem encoding" (sys.getfilesystemencoding()) at runtime: it doesn't work.
The filesystem encoding must be set as soon as possible and must never change later. As soon as possible: before the first call to os.fsdecode(), which is implemented in C as Py_DecodeLocale(). For example, the encoding must be set before Python imports the first module. The filesystem encoding must be set before Python decodes *any* operating system data: command line arguments, any filename or path, environment variables, etc. Hopefully, Windows provides most operating system data as Unicode directly: command line arguments and environment variables are exposed as Unicode for example. os.fsdecode() and os.fsencode() have an important property: assert os.fsencode(os.fsdecode(data)) == data On Windows, the other property is maybe more imporant: assert os.fsdecode(os.fsencode(data)) == data If the property becomes false, for example if the filesystem encoding is changed at runtime, you get mojibake. Example: * os.fsdecode() decodes the filename b'h\xc3\xa9llo' from UTF-8 => 'h\xe9llo' * sys._enablelegacywindowsfsencoding() * os.fsencode() encodes the filename to cp1252 => you get 'h\xc3\xa9llo' instead of 'h\xe9llo', say hello to mojibake -- Sorry, I didn't play with sys._enablelegacywindowsfsencoding() on Windows. I don't know if it would "work" if sys._enablelegacywindowsfsencoding() is the first instruction of an application. I expect that Python almost decodes nothing at startup on Windows, so it may work. sys._enablelegacywindowsfsencoding() is a private method, so it shouldn't be used. Maybe we could add a "fuse" (flag only sets to 1, cannot be reset to 0) to raise an exception if sys._enablelegacywindowsfsencoding() is called "too late", after the first call to os.fsdecode() / Py_DecodeLocale()? ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue29241> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
