Revert "refactor: Enhance typing in udf.py by introducing Protocol for WindowEvaluator and improving import organization"

This reverts commit 16dbe5f.

Author: kosiew

python/datafusion/udf.py

@@ -22,16 +22,7 @@
 import functools
 from abc import ABCMeta, abstractmethod
 from enum import Enum
-from typing import (
-    TYPE_CHECKING,
-    Any,
-    Callable,
-    Optional,
-    Protocol,
-    runtime_checkable,
-    overload,
-    TypeVar,
-)
+from typing import TYPE_CHECKING, Any, Callable, Optional, TypeVar, overload
 
 import pyarrow as pa
 
@@ -438,9 +429,8 @@ def wrapper(*args: Any, **kwargs: Any) -> Expr:
         return _decorator(*args, **kwargs)
 
 
-@runtime_checkable
-class WindowEvaluator(Protocol):
-    """Protocol defining interface for user-defined window functions (UDWF).
+class WindowEvaluator:
+    """Evaluator class for user-defined window functions (UDWF).
 
     It is up to the user to decide which evaluate function is appropriate.
 
@@ -721,7 +711,7 @@ def _create_window_udf(
             msg = "`func` must be callable."
             raise TypeError(msg)
         if not isinstance(func(), WindowEvaluator):
-            msg = "`func` must implement the WindowEvaluator protocol"
+            msg = "`func` must implement the abstract base class WindowEvaluator"
             raise TypeError(msg)
 
         name = name or func.__qualname__.lower()

python/tests/test_udwf.py

@@ -218,7 +218,7 @@ def test_udwf_errors(complex_window_df):
 def test_udwf_errors_with_message():
     """Test error cases for UDWF creation."""
     with pytest.raises(
-        TypeError, match="`func` must implement the WindowEvaluator protocol"
+        TypeError, match="`func` must implement the abstract base class WindowEvaluator"
     ):
         udwf(
             NotSubclassOfWindowEvaluator, pa.int64(), pa.int64(), volatility="immutable"
@@ -466,51 +466,3 @@ def test_udwf_named_function(ctx, count_window_df):
         FOLLOWING) FROM test_table"""
     ).collect()[0]
     assert result.column(0) == pa.array([0, 1, 2])
-
-
-def test_window_evaluator_protocol(count_window_df):
-    """Test that WindowEvaluator works as a Protocol without explicit inheritance."""
-
-    # Define a class that implements the Protocol interface without inheriting
-    class CounterWithoutInheritance:
-        def __init__(self, base: int = 0) -> None:
-            self.base = base
-
-        def evaluate_all(self, values: list[pa.Array], num_rows: int) -> pa.Array:
-            return pa.array([self.base + i for i in range(num_rows)])
-
-        # Protocol methods with default implementations don't need to be defined
-
-    # Create a UDWF using the class that doesn't inherit from WindowEvaluator
-    protocol_counter = udwf(
-        CounterWithoutInheritance, pa.int64(), pa.int64(), volatility="immutable"
-    )
-
-    # Use the window function
-    df = count_window_df.select(
-        protocol_counter(column("a"))
-        .window_frame(WindowFrame("rows", None, None))
-        .build()
-        .alias("count")
-    )
-
-    result = df.collect()[0]
-    assert result.column(0) == pa.array([0, 1, 2])
-
-    # Also test with constructor args
-    protocol_counter_with_args = udwf(
-        lambda: CounterWithoutInheritance(10),
-        pa.int64(),
-        pa.int64(),
-        volatility="immutable",
-    )
-
-    df = count_window_df.select(
-        protocol_counter_with_args(column("a"))
-        .window_frame(WindowFrame("rows", None, None))
-        .build()
-        .alias("count")
-    )
-
-    result = df.collect()[0]
-    assert result.column(0) == pa.array([10, 11, 12])