[Python-ideas] Cross-platform pickling of Path objects

Ethan Furman ethan at stoneleaf.us
Fri Jul 15 20:57:50 EDT 2016

On 07/15/2016 05:51 PM, Antony Lee wrote:

> I have opened http://bugs.python.org/issue27175 a month and a half ago but didn't get any feedback there, so I'll copy-paste it here for comments:
> Currently, pickling Path objects lead to issues when working across platforms: Paths (and, thus, objects that contain Paths) created on a POSIX platform (PosixPaths) cannot be unpickled on Windows and vice versa.  There are a few possibilities around this issue.
> - Don't do anything about it, you should use PurePaths if you care about cross-platform compatibility: this would be pretty awkward, as any call to the Path API would require converting back the PurePath to a Path first.
> - Silently convert Paths to PurePaths during pickling (a solution that seems to have been adopted by http://docs.menpo.org/en/stable/api/menpo/io/export_pickle.html for example): it would be better if Paths at least roundtripped correctly within a single platform.
> - Convert Paths to PurePaths at unpickling time, only if the platform is different (and possibly with a warning): this is the least bad solution I came up with so far.  Note that calls to the Path API on a "converted" PurePath object would be invalid anyways as the PurePath (being of a different platform) cannot be representing a valid path.
> Thoughts?

Any use-case examples?  That would help in deciding on the best path forward.


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