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os.path.commonprefix returns insane results #158994
Description
Activity
Please see the documentation for newer versions, it now clearly explains what the function does, and why it's probably not what you want. You may also find this blog post interesting: https://sethmlarson.dev/deprecate-confusing-apis-like-os-path-commonprefix
Incredible that this one survived all the way to 3.5 and beyond when many, many other functions were quite happily simply backwards-incompatibly broken. Amazing. Anyway.
Your hyperbolic language is unnecessary and a blemish on your reputation.
Sorry you took it personally. I think the blog post linked earlier captures the surprise of the wider community over the course of decades quite well, and on the basis that this exact behaviour has been involved in (multiple) CVE security issues I disagree on the characterisation of my language as "hyperbolic". To each their own, thanks for Python, we love it despite its occasional weirdness regardless.
Bug report
This is clearly not a sane result.
To be clear, a sane result would look like
''
for the first example, and
'/'
for the second example.
This would then be consistent with how the module behaves for other examples:
This is also insane:
The returned example is not a "path". It is not a 'path prefix' in any meaningful sense. This is just a string match up to the point the string changes. It has nothing whatsoever to do with the notion of a 'path'.
CPython versions tested on:
3.12
Operating systems tested on:
Linux