v4.18.0a1

What's Changed

This release majorly rehaul's the way in which JSON Schema reference resolution is configured.
It does so in a way that should be backwards compatible, preserving old behavior whilst emitting deprecation warnings.

jsonschema.RefResolver is now deprecated in favor of the new referencing library.
referencing will begin in beta, but already is more compliant than the existing $ref support.
This change is a culmination of a meaningful chunk of work to make $ref resolution more flexible and more correct.
Backwards compatibility should be preserved for existing code which uses RefResolver, though doing so is again now deprecated, and all such use cases should be doable using the new APIs.
Please file issues on the referencing tracker if there is functionality missing from it, or here on the jsonschema issue tracker if you have issues with existing code not functioning the same, or with figuring out how to change it to use referencing.

For full details see the new referencing documentation.

Further changes

• Support for Python 3.7 has been dropped, as it is nearing end-of-life.
  This should not be a "visible" change in the sense that requires-python has been updated, so users using 3.7 should still receive v4.17.3 when installing the library.
• A small number of type annotations have been improved
• On draft 2019-09, unevaluatedItems now properly does not consider items to be evaluated by an additionalItems schema if items is missing from the schema, as the specification says in this case that additionalItems must be completely ignored.

Deprecations

• jsonschema.RefResolver -- see above for details on the replacement
• jsonschema.RefResolutionError -- see above for details on the replacement
• importing jsonschema.ErrorTree -- instead import it via jsonschema.exceptions.ErrorTree
• importing jsonschema.FormatError -- instead import it via jsonschema.exceptions.FormatError

New Contributors

• @DanielNoord made their first contribution in #1021

Full Changelog: v4.17.3...v4.18.0a1