[Python-Dev] When should pathlib stop being provisional? (original) (raw)

Wes Turner wes.turner at gmail.com
Wed Apr 6 17:03:05 EDT 2016

On Apr 6, 2016 12:47 PM, "Brett Cannon" <brett at python.org> wrote:

On Wed, 6 Apr 2016 at 10:41 Wes Turner <wes.turner at gmail.com> wrote: * +1 for path, fspath (though I don't know what each does) Returns a string representing a file system path.

Why two methods? uripath?

(scheme, host (port), path, query, fragment) so, not uripath

what would be the difference between path and fspath?

* why not Text(basestring / bytestring) and pathlib.Path(Text)? See the points about next() vs next()

Path(b'123') / u'456'

similarly, Path(b'123') / UTF8 / UTF16

* are there examples of cases where this cannot be? I don't understand what you think "cannot be".

What one recommends (path.py(str) / str(pathlib.Path()) + getattr) is distinct from what any given programmer chooses to do with their code.

* if not, +1 for subclassing str/Text * where are the examples of method collisions between the str interface and the pathlib.Path interface? There aren't any and that's partially why some people wanted the str subclass to begin with. Please consider this thread a str-subclass-free zone. This line of discussion is to flesh out the proposal for a path protocol as a proposal against subclassing str, not to settle the whole discussion outright. If you want to continue to debate the subclassing-str side of this please use the other thread.

this seems to be a sudden, arbitrary distinction.

are these proposals necessarily disjoint?

so, adding getattr(path, 'path', path) to stdlib and other code is going to prevent which edge cases (before os.path.normpath()* anyway) for which benefit?

when do I do getattr(path, 'fspath', path)?

-Brett

* str.div is nonsensical * pathlib.Path.div is super-useful

ah, not .add() but .append()

I suppose the request here is for the cases which would be prevented (that we need to learn to look for)

On Apr 6, 2016 10:10 AM, "Ethan Furman" <ethan at stoneleaf.us> wrote: On 04/05/2016 11:57 PM, Nick Coghlan wrote: On 6 April 2016 at 16:53, Nathaniel Smith <njs at pobox.com> wrote:

On Tue, Apr 5, 2016 at 11:29 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:

I'd missed the existing precedent in DirEntry.path, so simply taking that and running with it sounds good to me.

This makes me twitch slightly, because NumPy has had a whole set of problems due to the ancient and minimally-considered decision to assume a bunch of ad hoc non-namespaced method names fulfilled some protocol -- like all .sum methods will have a signature that's compatible with numpy's, and if an object has a .log method then surely that computes the logarithm (what else in computing could "log" possibly refer to?), etc. This experience may or may not be relevant, I'm not sure -- sometimes these kinds of twitches are good guides to intuition, and sometimes they are just knee-jerk responses to an old and irrelevant problem :-) But you might want to at least think about how common it might be to have existing objects with unrelated attributes that happen to be called "path", and the bizarro problems that might be caused if someone accidentally passes one of them to a function that expects all .path attributes to be instances of this new protocol. sys.path, for example. That's why I'd actually prefer the implicit conversion protocol to be the more explicitly named "fspath", with suitable "fspath = path" assignments added to DirEntry and pathlib. However, I'm also not offering to actually do the work here, and the casting vote goes to the folks pursuing the implementation effort. If we decide upon fspath (or path) I will do the work on pathlib and scandir to add those attributes. -- Ethan

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