[Python-Dev] Pathlib enhancements - acceptable inputs and outputs for __fspath__ and os.fspath()

[Chris Angelico]

On Wed, Apr 20, 2016 at 1:16 PM, Stephen J. Turnbull <stephen at xemacs.org> wrote:
> Brett Cannon writes:
>
>  > Now if you can convince me that the use of bytes paths is very
>  > minimal
>
> I doubt that I can do that, because all that Python 2 code is
> effectively bytes.  To the extent that people are just passing it into
> their bytes-domain code and it works for them, they probably "port" to
> Python 3 by using bytes for paths.  I just don't think bytes usage per
> se matters to the issue of polymorphism of __fspath__.
>

I would prefer to see this kind of code ported to Python 3 by using
native strings.

Python 2 code:

import json
with open(".config/obs-studio/basic/scenes/Standard.json") as f:
    data = json.load(f)
for scene in data["scene_order"]:
    print scene["name"]

Python 3 code:

import json
with open(".config/obs-studio/basic/scenes/Standard.json") as f:
    data = json.load(f)
for scene in data["scene_order"]:
    print(scene["name"])

The bulk of path string literals in Python programs will be all-ASCII.
Porting to Py3 won't fundamentally change this code, yet suddenly now
it's using Unicode strings. In reality, both versions of this example
are using *text* strings. The Py3 version has text in the source code,
a stream of Unicode codepoints in the runtime, and then (since I ran
this on Linux) encodes that to bytes for the file system. The Py2
version just does that conversion a little earlier: text in the source
code, a stream of eight-bit "texty bytes" in the runtime, and those
same bytes get given to the fs.

There's no reason to slap a b"..." prefix on every path for Py3. There
might be specific situations where you want that, but for the most
part, those paths came from human-readable text anyway, so they should
stay that way.

ChrisA