Add PyCapsule Type Support and Type Hint Enhancements for AggregateUDF in DataFusion Python Bindings #1277
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Implement fallback for PyCapsule-backed providers, ensuring type checkers are satisfied without protocol-aware stubs. Update typing imports and cast PyCapsule inputs in AggregateUDF.from_pycapsule for precise constructor typing.
…zation signatures
Introduce a _PyCapsule typing protocol to enable type checkers to recognize PyCapsule-based registrations. Restrict the AggregateUDF udaf overload to the PyCapsule protocol and update from_pycapsule to wrap raw capsule inputs using the internal binding directly.
Introduce a utility to validate PyCapsules and convert them into reusable DataFusion aggregate UDFs. Update PyAggregateUDF.from_pycapsule to handle raw PyCapsule inputs, leverage the new helper, and maintain existing provider fallback and error handling.
kosiew
commented
Oct 15, 2025
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| r"\b(?:pub\s+)?(?:struct|enum)\s+" | ||
| r"(?P<name>[A-Za-z_][A-Za-z0-9_]*)", |
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not related to this PR but this came up as a Ruff error.
timsaucer
reviewed
Oct 28, 2025
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| class _PyCapsule: | ||
| """Lightweight typing proxy for CPython ``PyCapsule`` objects.""" |
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Which issue does this PR close?
udaffunction #1237Rationale for this change
The current
AggregateUDF.udafandAggregateUDF.from_pycapsulemethods in the DataFusion Python API lack proper type hinting and handling for CPythonPyCapsuleobjects. This omission causes static type checking tools (e.g., mypy) to fail when users register UDAFs originating from external providers such asgeodatafusion, even though the runtime behavior functions correctly.This PR addresses the gap by explicitly supporting PyCapsule types both in type hints and runtime checks. By doing so, it improves type safety, developer experience, and code clarity while maintaining full backward compatibility.
example from #1237
Before
After
What changes are included in this PR?
TypeGuardfunction_is_pycapsule()for lightweight PyCapsule type validation._PyCapsuleproxy class for static typing compatibility in non-type-checking contexts.AggregateUDF.__init__andAggregateUDF.udaf()to includeAggregateUDFExportable | _PyCapsuleargument types.AggregateUDF.from_pycapsule()to support direct PyCapsule initialization.PyAggregateUDF::from_pycapsule()logic to delegate PyCapsule validation to a new helper functionaggregate_udf_from_capsule()for cleaner handling.Are these changes tested?
Yes:
Are there any user-facing changes?
Yes, minor improvements:
These changes are fully backward-compatible and non-breaking for existing user code.