[Python-Dev] PEP 594: update 1 (original) (raw)

Steve Dower steve.dower at python.org
Thu May 23 12:57:57 EDT 2019

On 23May2019 0947, Anders Munch wrote:

Fra: Paul Moore [mailto:p.f.moore at gmail.com]:

A major version change serves as a heads up that something is going on and you need to check the consequences before upgrading. Python's backward compatibility policy allows breaking changes between versions X.Y and X.Y+1 (with a suitable deprecation period). This proposal is no different. Except perhaps in scale. The same people that upgrade from 3.x to 3.x+1 without giving it a second thought, just to be on the latest version, will hesitate to go from 3.x to 4.y, because the major version change is a hint that they should be more careful. That means they're ready for it when they get the ModuleNotFoundError exception, instead of feeling ambushed. OK, it may be that this is not enough to warrant a 4.0 release, but I do think python-dev should get over its fear of major versions sometime. And that transitioning to a leaner standard library with some things moved to PyPI would not be a bad program statement for a Python 4.0.

We need to make it more clear somehow that Python uses series.major.minor.micro versioning, not SemVer. I see this confusion happen all the time.

Think of it as Python3 7.x moving to Python3 8.x, and evaluate how much effort you should put into migration :)

That said, I'm totally in favour of Python 4.0 being the point where we change expectations about what will be in the standard library (and also C API, language/implementation semantics, etc.).

But until we have a clear vision statement that everyone (or enough) is behind, there's nothing gained by prematurely causing that much disruption.

Cheers, Steve

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