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

Steven D'Aprano steve at pearwood.info
Wed Apr 6 06:45:08 EDT 2016

On Tue, Apr 05, 2016 at 11:53:05PM -0700, Nathaniel Smith wrote:

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.

It's the down-side of duck-typing. It's all well and good accepting anything with a quack method, but not everything is that straight- forward:

artist.draw() gunslinger.draw()

I think that file system paths are important enough, and tricky enough, to justify their own protocol. I like Nick's suggestion of a special dunder method for converting path-like objects into paths, without the problems that str(x) has, or the risk of assuming that anything with a .path attribute refers to a file system path.

(maze.path, garden.path, career.path perhaps?)

-- Steve

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