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

Nick Coghlan ncoghlan at gmail.com
Wed Apr 6 02:57:49 EDT 2016

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.

Cheers, Nick.

-- Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia

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