better handling of attrs and slots instances

pydra/utils/hash.py

@@ -106,15 +106,17 @@ def __bytes_repr__(self, cache: Cache) -> Iterator[bytes]:
 def bytes_repr(obj: object, cache: Cache) -> Iterator[bytes]:
     cls = obj.__class__
     yield f"{cls.__module__}.{cls.__name__}:{{".encode()
-    try:
-        dct = obj.__dict__
-    except AttributeError as e:
-        # Attrs creates slots classes by default, so we add this here to handle those
-        # cases
+    if attrs.has(type(obj)):
+        # Drop any attributes that aren't used in comparisons by default
+        dct = attrs.asdict(obj, recurse=False, filter=lambda a, _: bool(a.eq))  # type: ignore
+    else:
         try:
-            dct = attrs.asdict(obj, recurse=False)  # type: ignore
-        except attrs.exceptions.NotAnAttrsClassError:
-            raise TypeError(f"Cannot hash {obj} as it is a slots class") from e
+            dct = obj.__dict__
+        except AttributeError as e:
+            try:
+                dct = {n: getattr(obj, n) for n in obj.__slots__}  # type: ignore
+            except AttributeError:
+                raise e
     yield from bytes_repr_mapping_contents(dct, cache)
     yield b"}"
 

pydra/utils/tests/test_hash.py

@@ -135,6 +135,20 @@ def __init__(self, x):
     assert re.match(rb".*\.MyClass:{str:1:x=.{16}}", obj_repr)
 
 
+def test_bytes_repr_slots_obj():
+    class MyClass:
+        __slots__ = ("x",)
+
+        def __init__(
+            self,
+            x,
+        ):
+            self.x = x
+
+    obj_repr = join_bytes_repr(MyClass(1))
+    assert re.match(rb".*\.MyClass:{str:1:x=.{16}}", obj_repr)
+
+
 def test_bytes_repr_attrs_slots():
     @attrs.define
     class MyClass:
@@ -144,6 +158,15 @@ class MyClass:
     assert re.match(rb".*\.MyClass:{str:1:x=.{16}}", obj_repr)
 
 
+def test_bytes_repr_attrs_no_slots():
+    @attrs.define(slots=False)
+    class MyClass:
+        x: int
+
+    obj_repr = join_bytes_repr(MyClass(1))
+    assert re.match(rb".*\.MyClass:{str:1:x=.{16}}", obj_repr)
+
+
 def test_bytes_repr_type1():
     obj_repr = join_bytes_repr(Path)
     assert obj_repr == b"type:(pathlib.Path)"