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qapi/schema: Don't initialize "members" with None

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Declare, but don't initialize the "members" field with type
List[QAPISchemaObjectTypeMember].

This simplifies the typing from what would otherwise be
Optional[List[T]] to merely List[T]. This removes the need to add
assertions to several callsites that this value is not None - which it
never will be after the delayed initialization in check() anyway.

The type declaration without initialization trick will cause accidental
uses of this field prior to full initialization to raise an
AttributeError.

(Note that it is valid to have an empty members list, see the internal
q_empty object as an example. For this reason, we cannot use the empty
list as a replacement test for full initialization and instead rely on
the _checked/_check_complete fields.)

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: <20240315152301.3621858-17-armbru@redhat.com>
This commit is contained in:
John Snow 2024-03-15 16:22:52 +01:00 committed by Markus Armbruster
parent 875f624232
commit 9beda22dcb
1 changed files with 7 additions and 5 deletions
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12
scripts/qapi/schema.py
View file

@ -20,7 +20,7 @@
from collections import OrderedDict
import os
import re
from typing import List, Optional
from typing import List, Optional, cast
from .common import (
POINTER_SUFFIX,
@ -449,7 +449,7 @@ def __init__(self, name, info, doc, ifcond, features,
self.base = None
self.local_members = local_members
self.variants = variants
self.members = None
self.members: List[QAPISchemaObjectTypeMember]
self._check_complete = False
def check(self, schema):
@ -482,7 +482,11 @@ def check(self, schema):
for m in self.local_members:
m.check(schema)
m.check_clash(self.info, seen)
members = seen.values()
# self.check_clash() works in terms of the supertype, but
# self.members is declared List[QAPISchemaObjectTypeMember].
# Cast down to the subtype.
members = cast(List[QAPISchemaObjectTypeMember], list(seen.values()))
if self.variants:
self.variants.check(schema, seen)
@ -515,11 +519,9 @@ def is_implicit(self):
return self.name.startswith('q_')
def is_empty(self):
assert self.members is not None
return not self.members and not self.variants
def has_conditional_members(self):
assert self.members is not None
return any(m.ifcond.is_present() for m in self.members)
def c_name(self):