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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39754 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kQYCM-0006pn-Rv for qemu-devel@archiver.kernel.org; Thu, 08 Oct 2020 11:51:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58192) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kQYAZ-0005PB-Hc for qemu-devel@nongnu.org; Thu, 08 Oct 2020 11:49:27 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25035) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kQYAX-0002SB-1p for qemu-devel@nongnu.org; Thu, 08 Oct 2020 11:49:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602172164; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vh89ze9xd+EWtVHFBPaOOqel3MQAorfH7tny45RTgSA=; b=SZMuZw34Iv9Cyz0lr12G79JTp2niV8ifz3LZ3bOI/4Y3ye5anfi94mnbZHCK3h7KxrDqLf UxhENvPwhZ7gWa8PSr6O5Z+HtbBrVpnn69DSNTuvrXFWiLQ+uJS1T3D2vLCY+EcJbpiELe MB6wprcALqPKuheIKsCmGkBqK2r6WuI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-593-PbpMlZKlO92pgkrvwxTtgA-1; Thu, 08 Oct 2020 11:49:21 -0400 X-MC-Unique: PbpMlZKlO92pgkrvwxTtgA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 441DE8F68FD for ; Thu, 8 Oct 2020 15:49:20 +0000 (UTC) Received: from [10.10.120.38] (ovpn-120-38.rdu2.redhat.com [10.10.120.38]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3378277D42; Thu, 8 Oct 2020 15:49:19 +0000 (UTC) Subject: Re: [PATCH v5 34/36] qapi/visit.py: assert tag_member contains a QAPISchemaEnumType To: Markus Armbruster References: <20201005195158.2348217-1-jsnow@redhat.com> <20201005195158.2348217-35-jsnow@redhat.com> <87mu0yb40j.fsf@dusky.pond.sub.org> <87zh4x13z6.fsf@dusky.pond.sub.org> From: John Snow Message-ID: <23ca848a-b472-cb34-31d2-a0cefbdf27d8@redhat.com> Date: Thu, 8 Oct 2020 11:49:18 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <87zh4x13z6.fsf@dusky.pond.sub.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jsnow@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/08 02:56:27 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.214, 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 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Cleber Rosa , qemu-devel@nongnu.org, Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/8/20 5:06 AM, Markus Armbruster wrote: > John Snow writes: > >> On 10/7/20 8:43 AM, Markus Armbruster wrote: >>> John Snow writes: >>> >>>> This is true by design, but not presently able to be expressed in the >>>> type system. An assertion helps mypy understand our constraints. >>>> >>>> Signed-off-by: John Snow >>>> Reviewed-by: Eduardo Habkost >>>> Reviewed-by: Cleber Rosa >>>> --- >>>> scripts/qapi/visit.py | 12 +++++++----- >>>> 1 file changed, 7 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py >>>> index 14f30c228b7..4f11fd325b8 100644 >>>> --- a/scripts/qapi/visit.py >>>> +++ b/scripts/qapi/visit.py >>>> @@ -22,7 +22,7 @@ >>>> mcgen, >>>> ) >>>> from .gen import QAPISchemaModularCVisitor, ifcontext >>>> -from .schema import QAPISchemaObjectType >>>> +from .schema import QAPISchemaEnumType, QAPISchemaObjectType >>>> >>>> def gen_visit_decl(name, scalar=False): >>>> @@ -84,15 +84,17 @@ def gen_visit_object_members(name, base, members, variants): >>>> ret += gen_endif(memb.ifcond) >>>> if variants: >>>> + tag_member = variants.tag_member >>>> + assert isinstance(tag_member.type, QAPISchemaEnumType) >>> I'm curious: do you need the local variable to make the assertion >>> stick? >>> >> >> No, but it only sticks to the binding and not the >> data. i.e. assertions to downcast work on the *name*. > > Would it stick to variants.tag_member, too? > As long as variants isn't re-bound in that scope, it should stick within that scope, yeah. (I think. Didn't test. It's my expectation.) > I'm asking to learn, not to find a reason to make you change your patch. > >> (This comes up somewhere in the schema.py patches where I make a >> change that looks completely pointless, but it makes mypy happy.) >> >> I could have left it alone. I just saw a lot of repeated multi-dots >> and habitually created a temporary local for the purpose. > > Matter of taste. Long chains of dots make the code hard to read because > they are so long. Temporary variable make it hard to read because you > have to remember what they mean. Tradeoff. I come up with cases I find > hard to decide all too often. > > In case the local variable isn't needed for mypy: when you throw in > something that isn't needed for the patch's stated purpose, it's best to > mention it in the commit message, because not mentioning it is a review > comment magnet :) > > Put yourself in the reviewers shoes. Your lovingly crafted commit > message puts him into a positive mood. He nods along while reading your > obvious patch at a good pace. And then he runs smack into the > unexpected unrelated part, and stops: oh, what's going on here? Back up > some and read more slowly to make sure I understand. > Yeah, understood. Well, part of it is knowing the review style of your reviewer too. It's been a while since we've personally swapped patches. The actual process for much of this was: "There is an error! let me fix that error." And then I do that, but I do so using idioms and patterns I'm familiar or comfortable with. And then post-hoc, not 100% of them were necessarily required, strictly, to fix the problem. Most of this series was written "one file at a time", and then split out post-fact into little per-warning changes. I didn't even send part 1 until I finished typing the *entire* package, to make sure that things were as correct as possible from the very first commit. I often don't really even notice that little changes aren't strictly necessary until they're challenged, it's usually not a conscious choice to try and sneak stuff in. Still always trying to find a balance between "Easy to maintain and iterate" and "easy to review." Tough line for me. >>>> + >>>> ret += mcgen(''' >>>> switch (obj->%(c_name)s) { >>>> ''', >>>> - c_name=c_name(variants.tag_member.name)) >>>> + c_name=c_name(tag_member.name)) >>>> for var in variants.variants: >>>> - case_str = c_enum_const(variants.tag_member.type.name, >>>> - var.name, >>>> - variants.tag_member.type.prefix) >>>> + case_str = c_enum_const(tag_member.type.name, var.name, >>>> + tag_member.type.prefix) >>>> ret += gen_if(var.ifcond) >>>> if var.type.name == 'q_empty': >>>> # valid variant and nothing to do