Revert Addition of __new__ method.

changes/346.fixed

@@ -0,0 +1 @@
+Reverted addition of __new__ method to Adapter class to resolve instantiation issues.

diffsync/__init__.py

@@ -16,7 +16,6 @@
 """
 
 import sys
-from copy import deepcopy
 from inspect import isclass
 from typing import (
     Any,
@@ -482,19 +481,6 @@ def __init_subclass__(cls) -> None:
             if not isclass(value) or not issubclass(value, DiffSyncModel):
                 raise AttributeError(f'top_level references attribute "{name}" but it is not a DiffSyncModel subclass!')
 
-    def __new__(cls, **kwargs):  # type: ignore[no-untyped-def]
-        """Document keyword arguments that were used to initialize Adapter."""
-        meta_kwargs = {}
-        for key, value in kwargs.items():
-            try:
-                meta_kwargs[key] = deepcopy(value)
-            except Exception:  # pylint: disable=broad-exception-caught
-                # Some objects (e.g. Kafka Consumer, DB connections) cannot be deep copied
-                meta_kwargs[key] = value
-        instance = super().__new__(cls)
-        instance._meta_kwargs = meta_kwargs
-        return instance
-
     def __str__(self) -> StrType:
         """String representation of an Adapter."""
         if self.type != self.name:

tests/unit/test_diffsync.py

@@ -9,7 +9,6 @@
 from diffsync import Adapter, DiffSyncModel
 from diffsync.enum import DiffSyncFlags, DiffSyncModelFlags
 from diffsync.exceptions import DiffClassMismatch, ObjectAlreadyExists, ObjectCrudException, ObjectNotFound
-from diffsync.store.local import LocalStore
 
 from .conftest import BackendA, Device, Interface, PersonA, Site, TrackedDiff
 
@@ -1142,129 +1141,3 @@ def test_diffsync_get_initial_value_order():
         "interface",
         "person",
     ]
-
-
-def test_adapter_new_stores_kwargs():
-    """Test that __new__ stores keyword arguments in _meta_kwargs."""
-    adapter = Adapter(name="test_adapter")
-    assert hasattr(adapter, "_meta_kwargs")
-    assert adapter._meta_kwargs == {"name": "test_adapter"}  # pylint: disable=protected-access
-
-
-def test_adapter_new_with_no_kwargs():
-    """Test that __new__ works with no keyword arguments."""
-    adapter = Adapter()
-    assert hasattr(adapter, "_meta_kwargs")
-    assert adapter._meta_kwargs == {}  # pylint: disable=protected-access
-
-
-def test_adapter_new_with_multiple_kwargs():
-    """Test that __new__ stores multiple keyword arguments."""
-    adapter = Adapter(name="test", internal_storage_engine=LocalStore)
-    assert adapter._meta_kwargs == {  # pylint: disable=protected-access
-        "name": "test",
-        "internal_storage_engine": LocalStore,
-    }
-
-
-def test_adapter_new_with_subclass():
-    """Test that __new__ works correctly with Adapter subclasses."""
-    adapter = BackendA(name="test_backend")
-    assert hasattr(adapter, "_meta_kwargs")  # pylint: disable=protected-access
-    assert adapter._meta_kwargs == {"name": "test_backend"}  # pylint: disable=protected-access
-
-
-def test_adapter_new_independent_instances():
-    """Test that different Adapter instances have independent _meta_kwargs."""
-    adapter1 = Adapter(name="adapter1", internal_storage_engine=LocalStore)
-    adapter2 = Adapter(name="adapter2", internal_storage_engine=LocalStore)
-
-    assert adapter1._meta_kwargs["name"] == "adapter1"  # pylint: disable=protected-access
-    assert adapter1._meta_kwargs["internal_storage_engine"] == LocalStore  # pylint: disable=protected-access
-    assert adapter2._meta_kwargs["name"] == "adapter2"  # pylint: disable=protected-access
-    assert adapter2._meta_kwargs["internal_storage_engine"] == LocalStore  # pylint: disable=protected-access
-
-
-class _AdapterWithExtraKwargs(Adapter):
-    """Minimal Adapter subclass that accepts extra kwargs for testing __new__ serialization."""
-
-    def __init__(self, name=None, internal_storage_engine=LocalStore, **kwargs):
-        super().__init__(name=name, internal_storage_engine=internal_storage_engine)
-
-
-def test_adapter_new_serializable_objects_are_deep_copied():
-    """Test that serializable objects passed to __new__ are deep-copied into _meta_kwargs."""
-    mutable_config = {"host": "localhost", "port": 5432}
-    mutable_list = [1, 2, 3]
-    adapter = _AdapterWithExtraKwargs(
-        name="test",
-        config=mutable_config,
-        tags=mutable_list,
-        internal_storage_engine=LocalStore,
-    )
-
-    # Verify values are stored
-    assert adapter._meta_kwargs["config"] == {"host": "localhost", "port": 5432}  # pylint: disable=protected-access
-    assert adapter._meta_kwargs["tags"] == [1, 2, 3]  # pylint: disable=protected-access
-
-    # Mutate the original objects - _meta_kwargs should retain the original values (deep copy)
-    mutable_config["port"] = 9999
-    mutable_list.append(4)
-
-    assert adapter._meta_kwargs["config"] == {"host": "localhost", "port": 5432}  # pylint: disable=protected-access
-    assert adapter._meta_kwargs["tags"] == [1, 2, 3]  # pylint: disable=protected-access
-
-
-def test_adapter_new_non_serializable_type_error_stored_as_is():
-    """Test that objects raising TypeError on deepcopy are stored as-is in _meta_kwargs."""
-
-    class NonCopyableTypeError:
-        """Object that raises TypeError when deep-copied (e.g. DB connection, Kafka Consumer)."""
-
-        def __deepcopy__(self, memo=None):
-            raise TypeError("Cannot deep copy this object")
-
-    non_copyable = NonCopyableTypeError()
-    adapter = _AdapterWithExtraKwargs(name="test", non_copyable=non_copyable, internal_storage_engine=LocalStore)
-
-    assert adapter._meta_kwargs["non_copyable"] is non_copyable  # pylint: disable=protected-access
-
-
-def test_adapter_new_non_serializable_attribute_error_stored_as_is():
-    """Test that objects raising AttributeError on deepcopy are stored as-is in _meta_kwargs."""
-
-    class NonCopyableAttributeError:
-        """Object that raises AttributeError when deep-copied."""
-
-        def __deepcopy__(self, memo=None):
-            raise AttributeError("Cannot deep copy - missing attribute")
-
-    non_copyable = NonCopyableAttributeError()
-    adapter = _AdapterWithExtraKwargs(name="test", non_copyable=non_copyable, internal_storage_engine=LocalStore)
-
-    assert adapter._meta_kwargs["non_copyable"] is non_copyable  # pylint: disable=protected-access
-
-
-def test_adapter_new_mixed_serializable_and_non_serializable_kwargs():
-    """Test that __new__ handles mix of serializable and non-serializable kwargs correctly."""
-
-    class NonCopyable:
-        def __deepcopy__(self, memo=None):
-            raise TypeError("Cannot copy")
-
-    serializable_dict = {"key": "value"}
-    non_copyable = NonCopyable()
-
-    adapter = _AdapterWithExtraKwargs(
-        name="test",
-        config=serializable_dict,
-        connection=non_copyable,
-        internal_storage_engine=LocalStore,
-    )
-
-    # Serializable: deep-copied (independent copy)
-    assert adapter._meta_kwargs["config"] == {"key": "value"}  # pylint: disable=protected-access
-    assert adapter._meta_kwargs["config"] is not serializable_dict
-
-    # Non-serializable: stored by reference
-    assert adapter._meta_kwargs["connection"] is non_copyable  # pylint: disable=protected-access