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qapi/schema: declare type for QAPISchemaObjectTypeMember.type

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A QAPISchemaObjectTypeMember's type gets resolved only during .check().
We have QAPISchemaObjectTypeMember.__init__() initialize self.type =
None, and .check() assign the actual type.  Using .type before .check()
is wrong, and hopefully crashes due to the value being None.  Works.

However, it makes for awkward typing.  With .type:
Optional[QAPISchemaType], mypy is of course unable to see that it's None
before .check(), and a QAPISchemaType after.  To help it over the hump,
we'd have to assert self.type is not None before all the (valid) uses.
The assertion catches invalid uses, but only at run time; mypy can't
flag them.

Instead, declare .type in .__init__() as QAPISchemaType *without*
initializing it.  Using .type before .check() now certainly crashes,
which is an improvement.  Mypy still can't flag invalid uses, but that's
okay.

Addresses typing errors such as these:

qapi/schema.py:657: error: "None" has no attribute "alternate_qtype"  [attr-defined]
qapi/schema.py:662: error: "None" has no attribute "describe"  [attr-defined]

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240315152301.3621858-7-armbru@redhat.com>
This commit is contained in:
John Snow 2024-03-15 16:22:42 +01:00 committed by Markus Armbruster
parent 2418d1c43a
commit ec103961bf
1 changed files with 1 additions and 1 deletions
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scripts/qapi/schema.py
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@ -786,7 +786,7 @@ class QAPISchemaObjectTypeMember(QAPISchemaMember):
assert isinstance(f, QAPISchemaFeature)
f.set_defined_in(name)
self._type_name = typ
self.type = None
self.type: QAPISchemaType # set during check()
self.optional = optional
self.features = features or []