On 5/29/2018 6:06 AM, Petr Viktorin wrote:
Python 3.7 removes the undocumented internal import `os.errno`.
Among a couple of hundred others, including some from idlelib.
We consider that a an implementation detail, which can be changed *without notice* even in a bugfix release.
We core developers occasionally run a linter on our code, or someone does it for us. Those of us who like clean code attend to warnings such as 'unused import'. I removed a couple of idlelib inports because of someone else running flake8.
Projects that depend on it are incorrect and should be fixed.
I think we can agree that better warning of 'use of stdlib internal import' would be great.
On bpo-33666, there's a debate on whether the removal should be mentioned in release notes, on the grounds that it broke some projects, is used in quire a few tutorials/books/examples, and it's been working since Python 2.5 or so.
Since I agree that *this* removal may possibly have the greatest impact, and that the purpose of What's New is to help users, I am glad Guido spoke up to say 'do it'. See my reponse to his post for a suggested entry.
But here's the thing: the more I think about this, the less I consider `os.errno` as "undocumented". Here's what I consider a reasonable path a programmer might go through:
# Where do I find errno values? # Maybe it's in `os`, like all other basic platform bindings?
import os os.err<tab> os.errno os.error( help(os.errno) Help on built-in module errno: ... # Yup, There it is!
Suppose a naive beginner who confuses 'IDLE' with 'python' (they exist!) thinks "Where can I find re functions? How about 'pyshell'
import idlelib.pyshell as ps ps.<completion box>r<jumps to re><return>
help(ps.re) Help on module re:
!
Is that reasoning sound?
Do you claim that os.errno is more documented (by the 'official' docs and help) than idlelib.pyshell.re? -- Terry Jan Reedy