Remove python2.7 support

[ssteinbach]

Summary

Following the VFX platform, for which 2019 was the last version which included python 2.7 support, we are dropping python2.7 support starting with v0.16. This enables us to modernize the code base and remove a number of shims and bandaids.

Changes

• Sets VFX platform supported years as 2022, 2021, and 2020
• Removes Python2.7 support from the library
  • # python 2 blocks
  • version_info[0] < 3 blocks
  • try:...except ImportError:... blocks
• Removes Python2.7 build matrix lines from CI/github actions
• updates setup.py project metadata to drop 2.7 from versions
• Removes shim code that was bridging differences between python3 and python2
• modernizes to python3 patterns by running pyupgrade --py37-plus
  • makes a bunch of smaller changes, from visual inspection lots of "".format() -> f""

OTIOZ Note

We will follow this up with a PR proposing to change the ZIP_DEFLATED algorithm used by OTIOZ to use bzip2 or LZMA.

Closes #1395

[ssteinbach]

Review notes on a previous PR that I want to not lose track of: #1418 (comment)

[ssteinbach]

@JeanChristopheMorinPerso It looks like importlib.metadata is new in 3.8 - since we still have 3.7 on the list, I don't think we can use that quite yet.

[JeanChristopheMorinPerso]

@ssteinbach there is a backport on PyPI: https://pypi.org/project/importlib-metadata/. It's what I would call an official backport. Maybe we could use that?

[ssteinbach]

@JeanChristopheMorinPerso Ok got it. I think I'd like to split that out to a follow up PR.

[JeanChristopheMorinPerso]

Looks good to me. I just found one small thing to fix. Also, should we replace the next methods for __next__? For example https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio-bindings/otio_serializableObjects.cpp#L247.

There is also some leftover python 2 vs 3 in _core_utils.py:

• https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio/core/_core_utils.py#L39-L69
• https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio/core/_core_utils.py#L234
• https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio/core/_core_utils.py#L385

[codecov-commenter]

Codecov Report

Merging #1423 (944b791) into main (c5b1a8b) will increase coverage by 0.30%.
The diff coverage is 79.76%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1423      +/-   ##
==========================================
+ Coverage   86.08%   86.38%   +0.30%     
==========================================
  Files         201      201              
  Lines       21051    20860     -191     
  Branches     2461     2446      -15     
==========================================
- Hits        18121    18020     -101     
+ Misses       2328     2244      -84     
+ Partials      602      596       -6     

Flag	Coverage Δ
py-unittests	86.38% <79.76%> (+0.30%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...melineio_contrib/adapters/extern_maya_sequencer.py	0.00% <0.00%> (ø)
...ntrib/opentimelineio_contrib/adapters/extern_rv.py	0.00% <0.00%> (ø)
.../opentimelineio_contrib/adapters/ffmpeg_burnins.py	0.00% <0.00%> (ø)
contrib/opentimelineio_contrib/adapters/rv.py	15.75% <0.00%> (ø)
...timelineio/opentimelineio/algorithms/track_algo.py	89.61% <ø> (ø)
...neio/opentimelineio/console/autogen_version_map.py	25.64% <0.00%> (ø)
...timelineio/opentimelineio/plugins/python_plugin.py	89.23% <ø> (ø)
...c/py-opentimelineio/opentimelineio/schema/stack.py	80.00% <0.00%> (+13.33%)	⬆️
tests/test_cdl.py	95.00% <ø> (ø)
tests/test_image_sequence_reference.py	97.57% <0.00%> (-0.03%)	⬇️
... and 56 more

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[ssteinbach]

Looks good to me. I just found one small thing to fix. Also, should we replace the next methods for __next__? For example https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio-bindings/otio_serializableObjects.cpp#L247.

There is also some leftover python 2 vs 3 in _core_utils.py:

• https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio/core/_core_utils.py#L39-L69
• https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio/core/_core_utils.py#L234
• https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio/core/_core_utils.py#L385

Great catch! This led me to a bunch of other ones by searching for version_info shenanigans. Fixing shortly...

[ssteinbach]

Hm, I'm not sure why collections.abc classes are throwing Sphinx off, or why they're creeping into the doc build?

[JeanChristopheMorinPerso]

@ssteinbach I guess you found the issue (the extra ())?

[JeanChristopheMorinPerso]

I re-reviewed everything and it looks good to me!

I'll just ask a question again because I think it kind of got lost. Should we replace the next methods for __next__? For example https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/main/src/py-opentimelineio/opentimelineio-bindings/otio_serializableObjects.cpp#L247. I think it would be a good idea but can well be push to another PR since this PR is starting to be pretty big.

[ssteinbach]

Lets do that in a follow up PR. I'm not quite clear on what it means for the implementation, so I'd like to do that separately to test it

[ssteinbach]

Ok this looks good. The two follow up from this:

• switch to using importlib.metadata from pkgutil #1426
• @JeanChristopheMorinPerso comments about next->__next__