Move rez.vendor.version outside of rez.vendor

[JeanChristopheMorinPerso]

Rez's version and requirement classes live in a rez.vendor.version subpackage. This will become a problem as we grow and extract some things into their own plugins outside of the main repository.

These modules anyway were written by Allan entirely and were put into vendor because the goal was to eventually extract them and make them available on PyPI. But it turns out there is already enough version libraries on PyPI and ours are quite specific to rez.

I propose to move them outside of the vendor folder and make them first class citizens.

Current layout

rez.vendor.version.version

Public classes:

• VersionToken
• NumericToken
• AlphanumericVersionToken
• Version
• VersionRange

Public functions:

• reverse_sort_key

Private classes (starting with _) will eventually need to be made public when we start to add type hints into our code base.

rez.vendor.version.requirement

Public classes:

• VersionedObject
• Requirement
• RequirementList

rez.vendor.version.util

Public classes:

• VersionError
• ParseException

Public functions:

• dedup (though this should be private, not public).

Proposed layout

• rez.vendor.version -> rez.version
• rez.vendor.version.version -> rez.version._version
• rez.vendor.version.requirement -> rez.version._requirement
• rez.vendor.version.util -> rez.versino._util
• Re-export everything that should be public in rez.version (__init__.py). This will shorten the import path and will also explicitly state what is public and what isn't.

How to introduce this change

Rez doesn't have a defined public API. This raises questions on how we could do this change. Similar changes were previously done, so we have a precedent to look at.
rez.package_maker__, rez.package_resources_ and rez.packages_ were moved to rez.package_maker, rez.package_resources and rez.packages respectively.
On top of that, the original names were kept, but importing them will trigger deprecation warnings.

We could do something similar for the version modules. But we are not particularly good at deprecating things. And I also think that it would be quite fair if we simply removed the modules entirely from where they are right now since they lived in a vendor folder. If a user of rez imports these, they were kind of warned by the vendor name.

It could be a good occasion to bump the version fo rez from 2 to 3 and remove the deprecated stuff and also bump the minimum required python to 3.7 for prod installs (not API).

[JeanChristopheMorinPerso]

I'm trying something new. I created a discussion instead of an issue to see if the use of threads will make it easier to discuss. We can also convert to an issue if needed.

[JeanChristopheMorinPerso]

I created a PR that implements this proposal: #1534

[JeanChristopheMorinPerso]

This was released on 2.114.0.