Re: [PATCH v3 04/16] qapi/expr.py: Add assertion for union type 'check_dict'

[John Snow]

On 2/24/21 5:35 AM, Markus Armbruster wrote:
> John Snow <jsnow@redhat.com> writes:
>
> > mypy isn't fond of allowing you to check for bool membership in a
> > collection of str elements. Guard this lookup for precisely when we were
> > given a name.
> >
> > Signed-off-by: John Snow <jsnow@redhat.com>
> > Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> > Reviewed-by: Cleber Rosa <crosa@redhat.com>
> > ---
> >   scripts/qapi/expr.py | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
> > index 783282b53ce..138fab0711f 100644
> > --- a/scripts/qapi/expr.py
> > +++ b/scripts/qapi/expr.py
> > @@ -173,7 +173,9 @@ def check_type(value, info, source,
> >           raise QAPISemError(info,
> >                              "%s should be an object or type name" % source)
> >   
> > -    permit_upper = allow_dict in info.pragma.name_case_whitelist
> > +    permit_upper = False
> > +    if isinstance(allow_dict, str):
> > +        permit_upper = allow_dict in info.pragma.name_case_whitelist
> >   
> >       # value is a dictionary, check that each member is okay
> >       for (key, arg) in value.items():
>
> Busy-work like this can make me doubt typing is worth the notational
> overhead.

Or it's a good exercise in finding weird code smells. It was strange to 
promote an argument named "allow_dict" to actually store a name value, 
but it weren't me who did that.

> There must a less awkward way to plumb "upper case okay" through
> check_type() to check_name_is_str().  But we're typing what we have.

I rather suspect that Schema is the place to do it instead of in 
expr.py, but I've been focused on getting the typing in instead of doing 
my weirder cleanups.

I'd like to remove Pragma stuff from expr.py entirely. Not a now-thing.

--js