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bpo-32278: Allow dataclasses.make_dataclass() to omit type information. #5115

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Merged
ericvsmith merged 1 commit into from
Jan 6, 2018
Merged

bpo-32278: Allow dataclasses.make_dataclass() to omit type information. #5115

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20 changes: 14 additions & 6 deletions Lib/dataclasses.py
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Original file line number Diff line number Diff line change
Expand Up @@ -708,9 +708,10 @@ def _astuple_inner(obj, tuple_factory):
def make_dataclass(cls_name, fields, *, bases=(), namespace=None):
"""Return a new dynamically created dataclass.

The dataclass name will be 'cls_name'. 'fields' is an interable
of either (name, type) or (name, type, Field) objects. Field
objects are created by calling 'field(name, type [, Field])'.
The dataclass name will be 'cls_name'. 'fields' is an iterable
of either (name), (name, type) or (name, type, Field) objects. If type is
omitted, use the string 'typing.Any'. Field objects are created by
calling 'field(name, type [, Field])'.

C = make_class('C', [('a', int', ('b', int, Field(init=False))], bases=Base)

@ilevkivskyi ilevkivskyi Jan 6, 2018

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Here is a typo/unmatched paren: it should be ('a', int), not ('a', int'


Expand All @@ -730,12 +731,19 @@ class C(Base):
# Copy namespace since we're going to mutate it.
namespace = namespace.copy()

anns = collections.OrderedDict((name, tp) for name, tp, *_ in fields)
namespace['__annotations__'] = anns
anns = collections.OrderedDict()
for item in fields:
if len(item) == 3:
if isinstance(item, str):
name = item
tp = 'typing.Any'
elif len(item) == 2:
name, tp, = item
elif len(item) == 3:
name, tp, spec = item
namespace[name] = spec
anns[name] = tp

namespace['__annotations__'] = anns
cls = type(cls_name, bases, namespace)
return dataclass(cls)

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14 changes: 14 additions & 0 deletions Lib/test/test_dataclasses.py
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Expand Up @@ -2033,6 +2033,20 @@ def test_helper_make_dataclass_class_var(self):
self.assertEqual(C.y, 10)
self.assertEqual(C.z, 20)

def test_helper_make_dataclass_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'})

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',
'y': int,
'z': 'typing.Any'})

class TestDocString(unittest.TestCase):
def assertDocStrEqual(self, a, b):
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2018-01-06-15-15-34.bpo-32278.bGnGc0.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Make type information optional on dataclasses.make_dataclass(). If omitted,
the string 'typing.Any' is used.