[Python-Dev] Defining a path protocol (was: When should pathlib stop being provisional?) (original) (raw)

Chris Barker chris.barker at noaa.gov
Fri Apr 8 12:04:23 EDT 2016

On Fri, Apr 8, 2016 at 2:50 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:

On 7 April 2016 at 03:26, Brett Cannon <brett at python.org> wrote:

> Method or attribute? (changes what kind of one-liner you might use in > libraries, but I think historically all protocols have been methods and the > serialized string representation might be costly to build)

couldn't it be a property?

Method, as long as there's a helper function somewhere

what has the helper function got to do with whether it's a method or attribute (would we call a property an attribute here?)

Built-in? (name is dependent on #1 if we add one)

os.fspath (alongside os.fsencode and os.fsdecode) (Putting this in a module low in the dependency stack makes it easy for other modules to access without pulling in all of pathlib's dependencies)

Iike that -- though still =0.5 on having one at all -- this is only going to be used by the stdlib and other path-using libraries, not user code -- is that that hard to call obj.fspath() ?

Add the method/attribute to str? (I assume so, much like index() is on > int, but I have not seen it explicitly stated so I would rather clarify it)

I thought the whole point off all this is that not any old string can be a path! (whereas any int can be an index). Unless we go with Chris A's suggestion that this be a more generic lossless string protocol, rather than just for paths.

It's worth summarising in a PEP at least for communications purposes - very easy for folks that don't follow python-dev to miss otherwise.

I'd say add it to the existing pathlib PEP -- along with the extra discussion of why Path does not inherit from str.

-CHB

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Christopher Barker, Ph.D. Oceanographer

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