From c2aa056c489e3b94ccc7a328cb2b4ca2973fe830 Mon Sep 17 00:00:00 2001
From: Pieter Eendebak <pieter.eendebak@gmail.com>
Date: Mon, 8 Sep 2025 16:33:11 +0200
Subject: [PATCH 1/3] Improve performance of attr.astuple

---
 src/attr/_funcs.py  | 11 +++++++----
 tests/test_funcs.py | 16 ++++++++++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/attr/_funcs.py b/src/attr/_funcs.py
index c6f0a4cee..1adb50021 100644
--- a/src/attr/_funcs.py
+++ b/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(
                         (
diff --git a/tests/test_funcs.py b/tests/test_funcs.py
index 4c9460eaf..df6a7193f 100644
--- a/tests/test_funcs.py
+++ b/tests/test_funcs.py
@@ -499,6 +499,22 @@ 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:
     """

From eb3ced2678bf970852e7e1b7ddfb759e813e9ac4 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Mon, 8 Sep 2025 14:36:31 +0000
Subject: [PATCH 2/3] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 tests/test_funcs.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/test_funcs.py b/tests/test_funcs.py
index df6a7193f..b254e9898 100644
--- a/tests/test_funcs.py
+++ b/tests/test_funcs.py
@@ -516,6 +516,7 @@ class Int(int):
         assert type(result[0]) is Int
         assert type(result[1][0]) is Int
 
+
 class TestHas:
     """
     Tests for `has`.

From 57ee5cf0bd6e1f510655b16d6f8beac164156197 Mon Sep 17 00:00:00 2001
From: Hynek Schlawack <hs@ox.cx>
Date: Mon, 8 Sep 2025 17:44:58 +0200
Subject: [PATCH 3/3] Add news fragment

---
 changelog.d/1469.change.md | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/1469.change.md

diff --git a/changelog.d/1469.change.md b/changelog.d/1469.change.md
new file mode 100644
index 000000000..1903d3da2
--- /dev/null
+++ b/changelog.d/1469.change.md
@@ -0,0 +1 @@
+The performance of `attrs.astuple()` has been improved by 49–270%.