[Python-Dev] file system path protocol PEP (original) (raw)

Koos Zevenhoven k7hoven at gmail.com
Thu May 12 06:12:58 EDT 2016

On Thu, May 12, 2016 at 11:31 AM, Sven R. Kunze <srkunze at mail.de> wrote:

On 11.05.2016 18:43, Brett Cannon wrote:

Rationale ========= Historically in Python, file system paths have been represented as strings or bytes. This choice of representation has stemmed from C's own decision to represent file system paths as const char * [#libc-open]. While that is a totally serviceable format to use for file system paths, it's not necessarily optimal. At issue is the fact that while all file system paths can be represented as strings or bytes, not all strings or bytes represent a file system path. I can remember this argument being made during the discussion. I am not sure if that 100% correct as soon as we talk about PurePaths.

I had suggested an alternative wording for this (see my commit on the work on Rationale).

Proposal ========

This proposal is split into two parts. One part is the proposal of a protocol for objects to declare and provide support for exposing a file system path representation. https://docs.python.org/3/whatsnew/changelog.html says: "Add ‘path’ attribute to pathlib.Path objects, returning the same as str(), to make it more similar to DirEntry. Library code can now write getattr(p, ‘path’, p) to get the path as a string from a Path, a DirEntry, or a plain string. This is essentially a small one-off protocol." So, in order to promote the "small one-off protocol" to a more broader protocol, this PEP proposes a simple rename of .path to .fspath, is that correct?

Well, I have brought this up previously several times. Indeed I see this as a further development of that duck-typing compatiblity approach. However, while the .path attribute is prior art, it has not been in a release yet.

Unfortunately, I don't have anything to contribute to the open issues. All solutions have their pros and cons and everything that could be said has been said. I think you need to decide.

Surprising enough, there are new things being said all the time. But luckily there seem to be signs of convergence.

-- Koos

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