[Python-Dev] Bytes path support

"Martin v. Löwis" martin at v.loewis.de
Thu Aug 21 14:54:36 CEST 2014

Am 19.08.14 19:43, schrieb Ben Hoyt:
>>>> The official policy is that we want them [support for bytes paths in stdlib functions] to go away, but reality so far has not budged. We will continue to hold our breath though. :-)
>>> Does that mean that new APIs should explicitly not support bytes? I'm
>>> thinking of os.scandir() (PEP 471), which I'm implementing at the
>>> moment. I was originally going to make it support bytes so it was
>>> compatible with listdir, but maybe that's a bad idea. Bytes paths are
>>> essentially broken on Windows.
>> Bytes paths are "essential" on Unix, though, so I don't think we should
>> create new low-level APIs that don't support bytes.
> Fair enough. I don't quite understand, though -- why is the "official
> policy" to kill something that's "essential" on *nix?

I think the people defending the "Unix file names are just bytes" side
often miss an important detail: displaying file names to the user, and
allowing the user to enter file names.

A script that just needs to traverse a directory tree and look at files
by certain criteria can easily do so with not worrying about a text
interpretation of the file names.

When it comes to user interaction, it becomes apparent that, even on
Unix, file names are not just bytes. If you do "ls -l" in your shell,
the "system" (not just the kernel - but ultimately the terminal program,
which might be the console driver, or an X11 application) will interpret
the file name as having an encoding, and render them with a font.

So for Python, the question is: which of the use cases (processing
all files, vs. showing them to the user) should be better supported?
Python 3 took the latter as an answer, under the assumption that this
is the more common case.


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