[Python-Dev] Python version numbers

[Paul G]

That documentation seems like a "layman's explanation" of how semantic versioning works. I suspect anyone familiar with semantic versioning will read that and think, "Ah, yes, this is a semantic versioning scheme." 

Regardless of the semantics (har har) of whether Python "follows strict semantic versioning", a change to the versioning scheme (CalVer should be backwards compatible with SemVer, mind you, since (21, 0, 0) > (3, 8, 0)) should make it absolutely clear that Python is not following SemVer.

Counter-intuitively, I think the *fact* of pinning the major version number to 3 is a worse signal of "we're not going to break everything" than switching to CalVer could. By switching to CalVer, you are removing the *ability* to signal a discontinuous major breaking change just by the version number. It is very much a "burn your boats so you can't retreat" philosophy to versioning.

Of course, if we want to reserve the ability to have sudden and major breaking changes, then yes, sticking with the current semi-SemVer system is fine, but I suspect that the fact that minor releases can break backwards compatibility will be confusing and annoying for most people (not me, because I know about it and I test against nightly), and as long as there's a "3" in the "major" slot, people will speculate about the possibility of a "4".

On 04/03/2018 09:07 AM, Paul Moore wrote:
> On 3 April 2018 at 13:51, Paul G <paul at ganssle.io> wrote:
>> Maybe this has already been discussed ad nauseum, but is the idea here that Python will stay on Python 3.x, but also start breaking backwards compatibility with old versions? That would seem to be a violation of semantic versioning.
> 
> Python's versions don't follow strict semantic versioning. See
> https://docs.python.org/3/faq/general.html#how-does-the-python-version-numbering-scheme-work
> 
> Paul
> 

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