fix: Properly support Python 3.14 (#227)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: borchero <22455425+borchero@users.noreply.github.com>
Co-authored-by: Oliver Borchert <oliver.borchert@quantco.com>

Author: Copilot

dataframely/collection/_base.py

@@ -202,7 +202,11 @@ def _get_metadata(source: dict[str, Any]) -> Metadata:
             annotations = source["__annotations__"]
         elif sys.version_info >= (3, 14):
             if "__annotate_func__" in source:
-                annotations = source["__annotate_func__"](Format.VALUE)
+                annotate_func = source["__annotate_func__"]
+                # __annotate_func__ can be None in Python 3.14 when a class
+                # has no annotations or in certain metaclass scenarios
+                if annotate_func is not None and callable(annotate_func):
+                    annotations = annotate_func(Format.VALUE)
         for attr, kls in annotations.items():
             result.members[attr] = CollectionMeta._derive_member_info(
                 attr, kls, CollectionMember()

tests/collection/test_base.py

@@ -1,6 +1,8 @@
 # Copyright (c) QuantCo 2025-2025
 # SPDX-License-Identifier: BSD-3-Clause
 
+import sys
+
 import polars as pl
 import pytest
 from polars.testing import assert_frame_equal
@@ -110,3 +112,37 @@ def test_collect_all_optional() -> None:
     assert isinstance(out, MyCollection)
     assert len(out.first.collect()) == 3
     assert out.second is None
+
+
+@pytest.mark.skipif(sys.version_info < (3, 14), reason="Python 3.14+ only")
+def test_annotate_func_none_py314() -> None:
+    """Test that __annotate_func__ = None doesn't cause TypeError in Python 3.14.
+
+    In Python 3.14 with PEP 649, __annotate_func__ can be None when:
+    - A class has no annotations
+    - Annotations are being processed during certain import contexts
+    - Classes are created dynamically with __annotate_func__ set to None
+
+    This test ensures the metaclass handles this gracefully.
+    """
+    from typing import cast
+
+    from dataframely.collection._base import BaseCollection, CollectionMeta
+
+    # Create a namespace with __annotate_func__ = None
+    namespace = {
+        "__module__": "__main__",
+        "__qualname__": "TestCollection",
+        "__annotate_func__": None,
+    }
+
+    # This should not raise TypeError
+    TestCollection = CollectionMeta(
+        "TestCollection",
+        (dy.Collection,),
+        namespace,
+    )
+
+    # Verify it has no members (since there are no annotations)
+    # Cast to BaseCollection to satisfy mypy since CollectionMeta creates Collection classes
+    assert cast(type[BaseCollection], TestCollection).members() == {}