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Description
Hello,
Consider the following, where lock aims at making provided argument immutable.
@dataclass
class Works:
foo: Mapping
def lock(self) -> None:
self.foo = MappingProxyType(self.foo)It works great with mypy, no issue. Now imagine I want to enforce a bit more to foo by requesting it be compatible with a Movie. I would try the following, without success.
class Movie(TypedDict):
author: str
year: int
@dataclass
class Fails:
foo: Movie
def lock(self) -> None:
self.foo = MappingProxyType(self.foo) # error: Incompatible types in assignment (expression has type "MappingProxyType[str, object]", variable has type "Movie") [assignment]Is there an workaround? If not, is if a good idea to discuss the possibility of a TypedMapping, that would simply work as follow?
class Movie(TypedMapping): # New feature ?
author: str
year: int
@dataclass
class Fixed:
foo: Movie
def lock(self) -> None:
self.foo = MappingProxyType(self.foo) # Would workThanks for your time.
All the best!
Élie.