Re: [PATCH 08/19] qapi/schema: add static typing and assertions to lookup_type()

[Markus Armbruster]

John Snow <jsnow@redhat.com> writes:

> This function is a bit hard to type as-is; mypy needs some assertions to
> assist with the type narrowing.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/schema.py | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
> index a1094283828..3308f334872 100644
> --- a/scripts/qapi/schema.py
> +++ b/scripts/qapi/schema.py
> @@ -968,8 +968,12 @@ def lookup_entity(self, name, typ=None):
>              return None
>          return ent
>  
> -    def lookup_type(self, name):
> -        return self.lookup_entity(name, QAPISchemaType)
> +    def lookup_type(self, name: str) -> Optional[QAPISchemaType]:

Any particular reason not to delay the type hints until PATCH 16?

> +        typ = self.lookup_entity(name, QAPISchemaType)
> +        if typ is None:
> +            return None
> +        assert isinstance(typ, QAPISchemaType)
> +        return typ

Would

           typ = self.lookup_entity(name, QAPISchemaType)
           assert isinstance(typ, Optional[QAPISchemaType])
           return typ

work?

>  
>      def resolve_type(self, name, info, what):
>          typ = self.lookup_type(name)