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support propertied decorators #13008

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82849bd
support propertied decorators
graingert Jun 22, 2022
9311edd
support settered decorators
graingert Jun 22, 2022
0e071aa
put decorated property warning back for overloads
graingert Jun 22, 2022
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13 changes: 9 additions & 4 deletions mypy/semanal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -846,6 +846,8 @@ def analyze_overload_sigs_and_impl(
# that.
non_overload_indexes.append(i)
else:
if item.var.is_property:
self.fail("Decorated property not supported", item)
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this puts back the "Decorated property not supported" warning on overloads:

from typing import overload
class A:
    @overload  # E: An overloaded function outside a stub file must have an implementation
    def f(self) -> int: pass
    @property  # E: Decorated property not supported
    @overload
    def f(self) -> int: pass

item.func.is_overload = True
types.append(callable)
elif isinstance(item, FuncDef):
Expand Down Expand Up @@ -957,16 +959,16 @@ def analyze_property_with_multi_part_definition(self, defn: OverloadedFuncDef) -
deleted_items = []
for i, item in enumerate(items[1:]):
if isinstance(item, Decorator):
if len(item.decorators) == 1:
if len(item.decorators) >= 1:
node = item.decorators[0]
Comment on lines +962 to 963
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the first item must be the setter - any other decorator is after the setter:

good:

@foo.setter
@dec
def foo(self, ...):
    ...

bad:

@dec
@foo.setter
def foo(self, ...):
    ...

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@graingert graingert Jun 22, 2022 •
edited
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"@overload" support is still broken, however:

from typing import TypeVar, Generic, overload
from typing_extensions import Self

T_str_or_bytes = TypeVar("T_str_or_bytes", bound=str | bytes)


class Foo(Generic[T_str_or_bytes]):
    def __init__(self, v: T_str_or_bytes) -> None:
        self._v = v

    @property
    @overload
    def ham(self: Foo[str]) -> str:
        return self._v

    @property
    @overload  # E: Decorated property not supported
    def ham(self: Foo[bytes]) -> bytes:
        return self._v

if isinstance(node, MemberExpr):
if node.name == 'setter':
# The first item represents the entire property.
first_item.var.is_settable_property = True
# Get abstractness from the original definition.
item.func.is_abstract = first_item.func.is_abstract
else:
self.fail("Decorated property not supported", item)
else:
self.fail("Decorated property not supported", item)
item.func.accept(self)
else:
self.fail(f'Unexpected definition for property "{first_item.func.name}"',
Expand Down Expand Up @@ -1047,6 +1049,7 @@ def visit_decorator(self, dec: Decorator) -> None:
d.accept(self)
removed: List[int] = []
no_type_check = False
could_be_decorated_property = False
for i, d in enumerate(dec.decorators):
# A bunch of decorators are special cased here.
if refers_to_fullname(d, 'abc.abstractmethod'):
Expand Down Expand Up @@ -1094,14 +1097,16 @@ def visit_decorator(self, dec: Decorator) -> None:
removed.append(i)
else:
self.fail("@final cannot be used with non-method functions", d)
elif not dec.var.is_property:
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@graingert graingert Jun 22, 2022 •
edited
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if a decorator shows up before "is_property" gets set then it's

@decorator
@property
def foo(...)

else we are in the propertied decorator scenario:

@property
@decorator
def foo(...)

could_be_decorated_property = True
for i in reversed(removed):
del dec.decorators[i]
if (not dec.is_overload or dec.var.is_property) and self.type:
dec.var.info = self.type
dec.var.is_initialized_in_class = True
if not no_type_check and self.recurse_into_functions:
dec.func.accept(self)
if dec.decorators and dec.var.is_property:
if could_be_decorated_property and dec.decorators and dec.var.is_property:
self.fail('Decorated property not supported', dec)
if dec.func.is_abstract and dec.func.is_final:
self.fail(f"Method {dec.func.name} is both abstract and final", dec)
Expand Down
18 changes: 17 additions & 1 deletion test-data/unit/semanal-errors.test
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Expand Up @@ -1244,12 +1244,28 @@ class A:
@dec # E: Decorated property not supported
@property
def f(self) -> int: pass
@property # E: Decorated property not supported
@property
@dec
def g(self) -> int: pass
[builtins fixtures/property.pyi]
[out]

[case testDecoratedPropertySetter]
import typing
def dec(f): pass
class A:
@property
@dec
def f(self) -> int: pass
@f.setter
@dec
def f(self, v: int) -> None: pass
@dec # E: Decorated property not supported
@f.setter
def f(self, v: int) -> None: pass
[builtins fixtures/property.pyi]
[out]

[case testImportTwoModulesWithSameNameInFunction]
import typing
def f() -> None:
Expand Down