tests

validity/tests/test_utils/test_misc.py

@@ -1,9 +1,10 @@
 import operator
 from contextlib import nullcontext
+from dataclasses import dataclass
 
 import pytest
 
-from validity.utils.misc import reraise
+from validity.utils.misc import partialcls, reraise
 from validity.utils.version import NetboxVersion
 
 
@@ -64,3 +65,16 @@ def test_netbox_version(obj1, obj2, compare_results):
     operators = [operator.lt, operator.le, operator.eq, operator.ge, operator.gt]
     for op, expected_result in zip(operators, compare_results):
         assert op(obj1, obj2) is expected_result
+
+
+def test_partialcls():
+    @dataclass
+    class A:
+        a: int
+        b: int
+
+    A2 = partialcls(A, b=10)
+    assert A2(5) == A(5, 10)
+    assert A2(1, 2) == A(1, 2)
+    assert A2(a=3, b=4) == A(3, 4)
+    assert type(A2(1, 2)) is A

validity/utils/misc.py

@@ -1,9 +1,8 @@
 import inspect
 from concurrent.futures import ThreadPoolExecutor
 from contextlib import contextmanager, suppress
-from functools import partialmethod
 from itertools import islice
-from typing import TYPE_CHECKING, Any, Callable, Iterable, TypeVar
+from typing import TYPE_CHECKING, Any, Callable, Iterable
 
 from core.exceptions import SyncError
 from django.db.models import Q
@@ -87,13 +86,15 @@ def batched(iterable: Iterable, n: int, container: type = list):
         yield batch
 
 
-_T = TypeVar("_T", bound=type)
-
-
-def partialcls(cls: _T, *args, class_name: str | None = None, **kwargs) -> _T:
+def partialcls(cls, *args, **kwargs):
     """
-    Creates subclass of a given class with partially filled __init__ params
+    Returns partial class with args and kwargs applied to __init__.
+    All original class attributes are preserved. When called, returns original class instance
     """
-    class_name = class_name or cls.__name__
-    class_attributes = {"__init__": partialmethod(cls.__init__, *args, **kwargs)}
-    return type(cls.__name__, (cls,), class_attributes)
+
+    def __new__(_, *new_args, **new_kwargs):
+        new_args = args + new_args
+        new_kwargs = kwargs | new_kwargs
+        return cls(*new_args, **new_kwargs)
+
+    return type(cls.__name__, (cls,), {"__new__": __new__})