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Python docs say that properties can have individual abstract parts: https://docs.python.org/3/library/abc.html#abc.abstractproperty
So, let's see what mypy thinks about it.
abstract getter
import abc
class Base(abc.ABC):
@property
@abc.abstractmethod
def x(self) -> int: ...
class Child(Base):
...
c = Child() # error: Cannot instantiate abstract class "Child" with abstract attribute "x"It is supported ✅
abstract setter
import abc
class Base(abc.ABC):
@property
def x(self) -> int: ...
@x.setter
@abc.abstractmethod
def x(self, arg: int) -> None: ...
class Child(Base):
...
c = Child()
c.x = 2
reveal_type(c) # Revealed type is "ex.Child"
# Runtime:
# TypeError: Can't instantiate abstract class Child with abstract method xNot supported 🚫
Should instead say: # error: Cannot instantiate abstract class "Child" with abstract attribute "x"
Or even better with abstract property setter "x"
abstract getter and setter
import abc
class Base(abc.ABC):
@property
@abc.abstractmethod
def x(self) -> int: ...
@x.setter
@abc.abstractmethod
def x(self, arg: int) -> None: ...
class Child(Base):
...
c = Child() # E: Cannot instantiate abstract class "Child" with abstract attribute "x"However, this does not fully cover this case:
import abc
class Base(abc.ABC):
@property
@abc.abstractmethod
def x(self) -> int: ...
@x.setter
@abc.abstractmethod
def x(self, arg: int) -> None: ...
class Child(Base):
@property # E: Read-only property cannot override read-write property
def x(self) -> int: ...
Child() # okWe can add additional note about x.setter being abstract. Or we can keep this as is.
Related: