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type redefinition allowed when value coming from dictionary #8123
Description
def kk(self, dic: Dict[str, str]) -> None:
a = 2
a = dic.get("as", "as2")
correctly complains that the type of a has changed:
error: Incompatible types in assignment (expression has type "Optional[str]", variable has type "int") [assignment]
However
def kk(self, dic: Dict) -> None:
a = 2
a = dic.get("as", "default")
does not complain that a type could be changed to str due to the default value in the get call.
Additionally, I'm not sure if the code below should complain since the dictionary may potentially return any type
def kk(self, dic: Dict) -> None:
a = 2
a = dic.get("as")
thanks!
Activity
msullivan commentedon Dec 10, 2019
The last example is certainly correct behavior.
The main example is a little hairy. The cause here is that the typeshed stub for
getisdef get(self, k: _KT, default: Union[_VT_co, _T]) -> Union[_VT_co, _T]: ....If we changed the definition to the more obvious
def get(self, k: _KT, default: _T) -> Union[_VT_co, _T]: ..., then I think this would work. That change did get made, but we had to revert it because it caused issues python/typeshed#2817.I think our conclusion was that #6613 would allow doing that. So I am going to close this issue in favor of that one but add a note to it. Thanks!
dpinol commentedon Dec 10, 2019
thank you guys, mypy is amazing