John Snow <js...@redhat.com> writes: > On Wed, Nov 22, 2023 at 7:09 AM Markus Armbruster <arm...@redhat.com> wrote: >> >> John Snow <js...@redhat.com> writes: >> >> > On Tue, Nov 21, 2023, 9:21 AM Markus Armbruster <arm...@redhat.com> wrote: >> > >> >> John Snow <js...@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 <js...@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]:
[...] >> >> > + 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? >> >> >> > >> > I don't *think* so, Optional isn't a runtime construct. >> >> Let me try... >> >> $ python >> Python 3.11.5 (main, Aug 28 2023, 00:00:00) [GCC 12.3.1 20230508 (Red >> Hat 12.3.1-1)] on linux >> Type "help", "copyright", "credits" or "license" for more information. >> >>> from typing import Optional >> >>> x=None >> >>> isinstance(x, Optional[str]) >> True >> >>> > > Huh. I ... huh! > > Well, this apparently only works in Python 3.10!+ > > TypeError: Subscripted generics cannot be used with class and instance checks We should be able to use it "soon" after 3.9 reaches EOL, approximately October 2025. *Sigh* >> >> > We can combine it >> > into "assert x is None or isinstance(x, foo)" though - I believe that's >> > used elsewhere in the qapi generator. >> >> >> > >> >> > def resolve_type(self, name, info, what): >> >> > typ = self.lookup_type(name) >> >> >> >> >>
