pyrsistent no longer supports Python2.7

[haneefkassam]

As of September 8, 2020, the jsonschema package no longer supports Python2.7, but not because of code it contributed, but because of a restriction placed on a dependent package (Pyrsistent). As of the aformentioned date, Pyrsistent no longer supports a Python version < 3.5 ( https://github.com/tobgu/pyrsistent/blob/ccc4a341ea74f80df8487654bfc7c638865867d4/setup.py#L81 ).

This would be fine and dandy, except for the way jsonschema defines dependencies, meaning I could pull an older version of jsonschema, but when it resolves its dependencies, it'll pull the most recent version of Pyrsistent (as seen in the setup.cfg of version as far back as Jan, 2019 - https://github.com/Julian/jsonschema/blob/21838cd7727bd7c1d9a309df51cd32ebb0c78cdb/setup.cfg#L28 ).

I get that Python2.7 is no longer supported, but I would expect older versions that previously worked on Python2.7 to continue to work on Python2.7.

[Julian]

Hi! Python 2.7 is very much still supported in 3.2, but this is a pyrsistent bug. See some of the closed issues for a link to the upstream ticket. I think #735 or #734.

[haneefkassam]

Any suggestion of a workaround? Can I force a pyrsistent version for jsonschema dependency?

Also, I'm a bit confused....how could you say that jsonschema supports python2.7 when one of its dependencies definitely does not?

[Julian]

pip install jsonschema pyrsistent==0.16.0 or thereabouts.

You should always be pinning your dependencies in wherever you're using jsonschema, for exactly this scenario (where a transitive dependency has a bug and forgets to do something or other and it breaks your app)

[haneefkassam]

OK, I'll give that a shot. Thank you!