https://github.com/python/cpython/commit/bb5ec6ea6e2fd270882dd9244c7d050882470095
commit: bb5ec6ea6e2fd270882dd9244c7d050882470095
branch: main
author: Jelle Zijlstra <jelle.zijls...@gmail.com>
committer: JelleZijlstra <jelle.zijls...@gmail.com>
date: 2025-05-05T08:21:32-07:00
summary:
gh-82129: Improve annotations for make_dataclass() (#133406)
Co-authored-by: sobolevn <m...@sobolevn.me>
Co-authored-by: Carl Meyer <c...@oddbird.net>
files:
A Misc/NEWS.d/next/Library/2024-09-18-09-15-40.gh-issue-82129.GQwt3u.rst
M Lib/dataclasses.py
M Lib/test/test_dataclasses/__init__.py
diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 0f7dc9ae6b82f5..86d29df0639184 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -244,6 +244,10 @@ def __repr__(self):
property,
})
+# Any marker is used in `make_dataclass` to mark unannotated fields as `Any`
+# without importing `typing` module.
+_ANY_MARKER = object()
+
class InitVar:
__slots__ = ('type', )
@@ -1591,7 +1595,7 @@ class C(Base):
for item in fields:
if isinstance(item, str):
name = item
- tp = 'typing.Any'
+ tp = _ANY_MARKER
elif len(item) == 2:
name, tp, = item
elif len(item) == 3:
@@ -1610,15 +1614,49 @@ class C(Base):
seen.add(name)
annotations[name] = tp
+ # We initially block the VALUE format, because inside dataclass() we'll
+ # call get_annotations(), which will try the VALUE format first. If we
don't
+ # block, that means we'd always end up eagerly importing typing here, which
+ # is what we're trying to avoid.
+ value_blocked = True
+
+ def annotate_method(format):
+ def get_any():
+ match format:
+ case annotationlib.Format.STRING:
+ return 'typing.Any'
+ case annotationlib.Format.FORWARDREF:
+ typing = sys.modules.get("typing")
+ if typing is None:
+ return annotationlib.ForwardRef("Any", module="typing")
+ else:
+ return typing.Any
+ case annotationlib.Format.VALUE:
+ if value_blocked:
+ raise NotImplementedError
+ from typing import Any
+ return Any
+ case _:
+ raise NotImplementedError
+ annos = {
+ ann: get_any() if t is _ANY_MARKER else t
+ for ann, t in annotations.items()
+ }
+ if format == annotationlib.Format.STRING:
+ return annotationlib.annotations_to_string(annos)
+ else:
+ return annos
+
# Update 'ns' with the user-supplied namespace plus our calculated values.
def exec_body_callback(ns):
ns.update(namespace)
ns.update(defaults)
- ns['__annotations__'] = annotations
# We use `types.new_class()` instead of simply `type()` to allow dynamic
creation
# of generic dataclasses.
cls = types.new_class(cls_name, bases, {}, exec_body_callback)
+ # For now, set annotations including the _ANY_MARKER.
+ cls.__annotate__ = annotate_method
# For pickling to work, the __module__ variable needs to be set to the
frame
# where the dataclass is created.
@@ -1634,10 +1672,13 @@ def exec_body_callback(ns):
cls.__module__ = module
# Apply the normal provided decorator.
- return decorator(cls, init=init, repr=repr, eq=eq, order=order,
- unsafe_hash=unsafe_hash, frozen=frozen,
- match_args=match_args, kw_only=kw_only, slots=slots,
- weakref_slot=weakref_slot)
+ cls = decorator(cls, init=init, repr=repr, eq=eq, order=order,
+ unsafe_hash=unsafe_hash, frozen=frozen,
+ match_args=match_args, kw_only=kw_only, slots=slots,
+ weakref_slot=weakref_slot)
+ # Now that the class is ready, allow the VALUE format.
+ value_blocked = False
+ return cls
def replace(obj, /, **changes):
diff --git a/Lib/test/test_dataclasses/__init__.py
b/Lib/test/test_dataclasses/__init__.py
index 99fefb57fd0f09..ac78f8327b808e 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -5,6 +5,7 @@
from dataclasses import *
import abc
+import annotationlib
import io
import pickle
import inspect
@@ -12,6 +13,7 @@
import types
import weakref
import traceback
+import sys
import textwrap
import unittest
from unittest.mock import Mock
@@ -25,6 +27,7 @@
import dataclasses # Needed for the string "dataclasses.InitVar[int]" to work
as an annotation.
from test import support
+from test.support import import_helper
# Just any custom exception we can catch.
class CustomError(Exception): pass
@@ -3754,7 +3757,6 @@ class A(WithDictSlot): ...
@support.cpython_only
def test_dataclass_slot_dict_ctype(self):
# https://github.com/python/cpython/issues/123935
- from test.support import import_helper
# Skips test if `_testcapi` is not present:
_testcapi = import_helper.import_module('_testcapi')
@@ -4246,16 +4248,56 @@ def test_no_types(self):
C = make_dataclass('Point', ['x', 'y', 'z'])
c = C(1, 2, 3)
self.assertEqual(vars(c), {'x': 1, 'y': 2, 'z': 3})
- self.assertEqual(C.__annotations__, {'x': 'typing.Any',
- 'y': 'typing.Any',
- 'z': 'typing.Any'})
+ self.assertEqual(C.__annotations__, {'x': typing.Any,
+ 'y': typing.Any,
+ 'z': typing.Any})
C = make_dataclass('Point', ['x', ('y', int), 'z'])
c = C(1, 2, 3)
self.assertEqual(vars(c), {'x': 1, 'y': 2, 'z': 3})
- self.assertEqual(C.__annotations__, {'x': 'typing.Any',
+ self.assertEqual(C.__annotations__, {'x': typing.Any,
'y': int,
- 'z': 'typing.Any'})
+ 'z': typing.Any})
+
+ def test_no_types_get_annotations(self):
+ C = make_dataclass('C', ['x', ('y', int), 'z'])
+
+ self.assertEqual(
+ annotationlib.get_annotations(C,
format=annotationlib.Format.VALUE),
+ {'x': typing.Any, 'y': int, 'z': typing.Any},
+ )
+ self.assertEqual(
+ annotationlib.get_annotations(
+ C, format=annotationlib.Format.FORWARDREF),
+ {'x': typing.Any, 'y': int, 'z': typing.Any},
+ )
+ self.assertEqual(
+ annotationlib.get_annotations(
+ C, format=annotationlib.Format.STRING),
+ {'x': 'typing.Any', 'y': 'int', 'z': 'typing.Any'},
+ )
+
+ def test_no_types_no_typing_import(self):
+ with import_helper.CleanImport('typing'):
+ self.assertNotIn('typing', sys.modules)
+ C = make_dataclass('C', ['x', ('y', int)])
+
+ self.assertNotIn('typing', sys.modules)
+ self.assertEqual(
+ C.__annotate__(annotationlib.Format.FORWARDREF),
+ {
+ 'x': annotationlib.ForwardRef('Any', module='typing'),
+ 'y': int,
+ },
+ )
+ self.assertNotIn('typing', sys.modules)
+
+ for field in fields(C):
+ if field.name == "x":
+ self.assertEqual(field.type,
annotationlib.ForwardRef('Any', module='typing'))
+ else:
+ self.assertEqual(field.name, "y")
+ self.assertIs(field.type, int)
def test_module_attr(self):
self.assertEqual(ByMakeDataClass.__module__, __name__)
diff --git
a/Misc/NEWS.d/next/Library/2024-09-18-09-15-40.gh-issue-82129.GQwt3u.rst
b/Misc/NEWS.d/next/Library/2024-09-18-09-15-40.gh-issue-82129.GQwt3u.rst
new file mode 100644
index 00000000000000..b8661f9eeaa5c9
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-09-18-09-15-40.gh-issue-82129.GQwt3u.rst
@@ -0,0 +1,2 @@
+Fix :exc:`NameError` when calling :func:`typing.get_type_hints` on a
:func:`dataclasses.dataclass` created by
+:func:`dataclasses.make_dataclass` with un-annotated fields.
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