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bpo-33453: Handle string type annotations in dataclasses. (GH-6768)

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Eric V. Smith 2018-05-15 22:44:27 -04:00 • committed by GitHub
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7 changed files with 399 additions and 20 deletions
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153
Lib/test/test_dataclasses.py
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@ -12,6 +12,9 @@ from typing import ClassVar, Any, List, Union, Tuple, Dict, Generic, TypeVar, Op
from collections import deque, OrderedDict, namedtuple
from functools import total_ordering
import typing # Needed for the string "typing.ClassVar[int]" to work as an annotation.
import dataclasses # Needed for the string "dataclasses.InitVar[int]" to work as an annotation.
# Just any custom exception we can catch.
class CustomError(Exception): pass
@ -600,7 +603,6 @@ class TestCase(unittest.TestCase):
class C:
x: ClassVar[typ] = Subclass()
def test_deliberately_mutable_defaults(self):
# If a mutable default isn't in the known list of
# (list, dict, set), then it's okay.
@ -924,14 +926,16 @@ class TestCase(unittest.TestCase):
z: ClassVar[int] = 1000
w: ClassVar[int] = 2000
t: ClassVar[int] = 3000
s: ClassVar = 4000
c = C(5)
self.assertEqual(repr(c), 'TestCase.test_class_var.<locals>.C(x=5, y=10)')
self.assertEqual(len(fields(C)), 2) # We have 2 fields.
self.assertEqual(len(C.__annotations__), 5) # And 3 ClassVars.
self.assertEqual(len(C.__annotations__), 6) # And 4 ClassVars.
self.assertEqual(c.z, 1000)
self.assertEqual(c.w, 2000)
self.assertEqual(c.t, 3000)
self.assertEqual(c.s, 4000)
C.z += 1
self.assertEqual(c.z, 1001)
c = C(20)
@ -939,6 +943,7 @@ class TestCase(unittest.TestCase):
self.assertEqual(c.z, 1001)
self.assertEqual(c.w, 2000)
self.assertEqual(c.t, 3000)
self.assertEqual(c.s, 4000)
def test_class_var_no_default(self):
# If a ClassVar has no default value, it should not be set on the class.
@ -2798,5 +2803,149 @@ class TestDescriptors(unittest.TestCase):
self.assertEqual(D.__set_name__.call_count, 1)
class TestStringAnnotations(unittest.TestCase):
def test_classvar(self):
# Some expressions recognized as ClassVar really aren't. But
# if you're using string annotations, it's not an exact
# science.
# These tests assume that both "import typing" and "from
# typing import *" have been run in this file.
for typestr in ('ClassVar[int]',
'ClassVar [int]'
' ClassVar [int]',
'ClassVar',
' ClassVar ',
'typing.ClassVar[int]',
'typing.ClassVar[str]',
' typing.ClassVar[str]',
'typing .ClassVar[str]',
'typing. ClassVar[str]',
'typing.ClassVar [str]',
'typing.ClassVar [ str]',
# Not syntactically valid, but these will
# be treated as ClassVars.
'typing.ClassVar.[int]',
'typing.ClassVar+',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
# x is a ClassVar, so C() takes no args.
C()
# And it won't appear in the class's dict because it doesn't
# have a default.
self.assertNotIn('x', C.__dict__)
def test_isnt_classvar(self):
for typestr in ('CV',
't.ClassVar',
't.ClassVar[int]',
'typing..ClassVar[int]',
'Classvar',
'Classvar[int]',
'typing.ClassVarx[int]',
'typong.ClassVar[int]',
'dataclasses.ClassVar[int]',
'typingxClassVar[str]',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
# x is not a ClassVar, so C() takes one arg.
self.assertEqual(C(10).x, 10)
def test_initvar(self):
# These tests assume that both "import dataclasses" and "from
# dataclasses import *" have been run in this file.
for typestr in ('InitVar[int]',
'InitVar [int]'
' InitVar [int]',
'InitVar',
' InitVar ',
'dataclasses.InitVar[int]',
'dataclasses.InitVar[str]',
' dataclasses.InitVar[str]',
'dataclasses .InitVar[str]',
'dataclasses. InitVar[str]',
'dataclasses.InitVar [str]',
'dataclasses.InitVar [ str]',
# Not syntactically valid, but these will
# be treated as InitVars.
'dataclasses.InitVar.[int]',
'dataclasses.InitVar+',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
# x is an InitVar, so doesn't create a member.
with self.assertRaisesRegex(AttributeError,
"object has no attribute 'x'"):
C(1).x
def test_isnt_initvar(self):
for typestr in ('IV',
'dc.InitVar',
'xdataclasses.xInitVar',
'typing.xInitVar[int]',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
# x is not an InitVar, so there will be a member x.
self.assertEqual(C(10).x, 10)
def test_classvar_module_level_import(self):
from . import dataclass_module_1
from . import dataclass_module_1_str
from . import dataclass_module_2
from . import dataclass_module_2_str
for m in (dataclass_module_1, dataclass_module_1_str,
dataclass_module_2, dataclass_module_2_str,
):
with self.subTest(m=m):
# There's a difference in how the ClassVars are
# interpreted when using string annotations or
# not. See the imported modules for details.
if m.USING_STRINGS:
c = m.CV(10)
else:
c = m.CV()
self.assertEqual(c.cv0, 20)
# There's a difference in how the InitVars are
# interpreted when using string annotations or
# not. See the imported modules for details.
c = m.IV(0, 1, 2, 3, 4)
for field_name in ('iv0', 'iv1', 'iv2', 'iv3'):
with self.subTest(field_name=field_name):
with self.assertRaisesRegex(AttributeError, f"object has no attribute '{field_name}'"):
# Since field_name is an InitVar, it's
# not an instance field.
getattr(c, field_name)
if m.USING_STRINGS:
# iv4 is interpreted as a normal field.
self.assertIn('not_iv4', c.__dict__)
self.assertEqual(c.not_iv4, 4)
else:
# iv4 is interpreted as an InitVar, so it
# won't exist on the instance.
self.assertNotIn('not_iv4', c.__dict__)
if __name__ == '__main__':
unittest.main()