Improve performance of attr.astuple

changelog.d/1469.change.md

@@ -0,0 +1 @@
+The performance of `attrs.astuple()` has been improved by 49–270%.

src/attr/_funcs.py

@@ -278,8 +278,11 @@ def astuple(
  v = getattr(inst, a.name)
  if filter is not None and not filter(a, v):
  continue
+ value_type = type(v)
  if recurse is True:
- if has(v.__class__):
+ if value_type in _ATOMIC_TYPES:
+ rv.append(v)
+ elif has(value_type):
  rv.append(
  astuple(
  v,
@@ -289,7 +292,7 @@ def astuple(
  retain_collection_types=retain,
  )
  )
- elif isinstance(v, (tuple, list, set, frozenset)):
+ elif issubclass(value_type, (tuple, list, set, frozenset)):
  cf = v.__class__ if retain is True else list
  items = [
  (
@@ -313,8 +316,8 @@ def astuple(
  # Workaround for TypeError: cf.__new__() missing 1 required
  # positional argument (which appears, for a namedturle)
  rv.append(cf(*items))
- elif isinstance(v, dict):
- df = v.__class__ if retain is True else dict
+ elif issubclass(value_type, dict):
+ df = value_type if retain is True else dict
  rv.append(
  df(
  (

tests/test_funcs.py

@@ -499,6 +499,23 @@ class A:
  with pytest.raises(TypeError, match=re.escape(message)):
  attr.astuple(instance, retain_collection_types=True)
 
+ def test_non_atomic_types(self, C):
+ """
+ Non-atomic types that don't have special treatment for are serialized
+ and the types are retained.
+ """
+
+ class Int(int):
+ pass
+
+ c = C(Int(10), [Int(1), 2])
+ expected = (Int(10), [Int(1), 2])
+
+ result = astuple(c)
+ assert expected == result
+ assert type(result[0]) is Int
+ assert type(result[1][0]) is Int
+
 
 class TestHas:
  """