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Tue, 12 Mar 2024 14:11:04 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFaWFzXH3UbfcxphGiW8cayAEirJRMd9V/PcoSU68gwyGuByB5xQC6QTz8uv+9Jy76IeGwhkyXFXpim9pcT2ZM= X-Received: by 2002:a05:6a20:160b:b0:1a3:152b:99f2 with SMTP id l11-20020a056a20160b00b001a3152b99f2mr3421221pzj.2.1710277864534; Tue, 12 Mar 2024 14:11:04 -0700 (PDT) MIME-Version: 1.0 References: <20240201224246.39480-1-jsnow@redhat.com> <20240201224246.39480-15-jsnow@redhat.com> <87y1bf5g9x.fsf@pond.sub.org> In-Reply-To: <87y1bf5g9x.fsf@pond.sub.org> From: John Snow Date: Tue, 12 Mar 2024 17:10:53 -0400 Message-ID: Subject: Re: [PATCH v3 14/20] qapi/schema: Don't initialize "members" with `None` To: Markus Armbruster Cc: qemu-devel@nongnu.org, Peter Maydell , Michael Roth Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.687, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Feb 20, 2024 at 10:03=E2=80=AFAM Markus Armbruster wrote: > > John Snow writes: > > > 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/_checking fields.) > > > > Signed-off-by: John Snow > > --- > > scripts/qapi/schema.py | 13 +++++++------ > > 1 file changed, 7 insertions(+), 6 deletions(-) > > > > diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py > > index a459016e148..947e7efb1a8 100644 > > --- a/scripts/qapi/schema.py > > +++ b/scripts/qapi/schema.py > > @@ -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, > > @@ -457,7 +457,7 @@ def __init__(self, name, info, doc, ifcond, feature= s, > > self.base =3D None > > self.local_members =3D local_members > > self.variants =3D variants > > - self.members =3D None > > + self.members: List[QAPISchemaObjectTypeMember] > > self._checking =3D False > > > > def check(self, schema): > > @@ -474,7 +474,7 @@ def check(self, schema): > > > > self._checking =3D True > > super().check(schema) > > - assert self._checked and self.members is None > > + assert self._checked > > This asserts state is "2. Being checked:. > > The faithful update would be > > assert self._checked and self._checking > > Or with my alternative patch > > assert self._checked and not self._check_complete > > > > seen =3D OrderedDict() > > if self._base_name: > > @@ -491,7 +491,10 @@ def check(self, schema): > > for m in self.local_members: > > m.check(schema) > > m.check_clash(self.info, seen) > > - members =3D seen.values() > > + > > + # check_clash is abstract, but local_members is asserted to be > > + # List[QAPISchemaObjectTypeMember]. Cast to the narrower type. > > What do you mean by "check_clash is abstract"? > > > + members =3D cast(List[QAPISchemaObjectTypeMember], list(seen.v= alues())) > > Do we actually need this *now*, or only later when we have more type > hints? > > > > > if self.variants: > > self.variants.check(schema, seen) > > @@ -524,11 +527,9 @@ def is_implicit(self): > > return self.name.startswith('q_') > > > > def is_empty(self): > > - assert self.members is not None > > This asserts state is "3. Checked". > > The faithful update would be > > assert self._checked and not self._checking > > Or with my alternative patch > > assert self._check_complete > > > return not self.members and not self.variants > > > > def has_conditional_members(self): > > - assert self.members is not None > > Likewise. Do we even need these assertions, though? If members isn't set, it's gonna crash anyway. I don't think you actually need them at all. I think it's fine to leave these changes in this patch and to remove the assertion as it no longer really guards anything. > > > return any(m.ifcond.is_present() for m in self.members) > > > > def c_name(self): > > This patch does two things: > > 1. Replace test of self.members (enabled by the previous patch) > > 2. Drop initialization of self.members and simplify the typing > > Observation, not demand. Wouldn't *mind* a split, though :) > I think maybe one of the assertions can be replaced in the previous patch, but I think everything else does really belong in this patch. --js