John Snow <js...@redhat.com> writes:
> On 4/25/21 3:27 AM, Markus Armbruster wrote:
>> John Snow <js...@redhat.com> writes:
>>
>>> The single quote token implies the value is a string. Assert this to be
>>> the case.
>>>
>>> Signed-off-by: John Snow <js...@redhat.com>
>>> ---
>>> scripts/qapi/parser.py | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py
>>> index 6b443b1247e..8d1fe0ddda5 100644
>>> --- a/scripts/qapi/parser.py
>>> +++ b/scripts/qapi/parser.py
>>> @@ -246,6 +246,8 @@ def get_members(self):
>>> raise QAPIParseError(self, "expected string or '}'")
>>> while True:
>>> key = self.val
>>> + assert isinstance(key, str) # Guaranteed by tok == "'"
>>> +
>>> self.accept()
>>> if self.tok != ':':
>>> raise QAPIParseError(self, "expected ':'")
>>
>> The assertion is correct, but I wonder why mypy needs it. Can you help?
>>
>
> The lexer value can also be True/False (Maybe None? I forget) based on
Yes, None for tokens like '{'.
> the Token returned. Here, since the token was the single quote, we know
> that value must be a string.
>
> Mypy has no insight into the correlation between the Token itself and
> the token value, because that relationship is not expressed via the type
> system.
I understand that mypy can't prove implications like if self.tok == "'",
then self.val is a str.
What I'm curious about is why key needs to be known to be str here.
Hmm, is it so return expr type-checks once you add -> OrderedDict[str,
object] to the function?
