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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]:53420 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kLcC3-0002IF-Un for qemu-devel@archiver.kernel.org; Thu, 24 Sep 2020 21:06:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53388) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kLbpx-0006HI-T3 for qemu-devel@nongnu.org; Thu, 24 Sep 2020 20:43:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58012) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kLbpw-0001sX-2v for qemu-devel@nongnu.org; Thu, 24 Sep 2020 20:43:45 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600994622; 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=AgU9/qR3kk5UkT+YBPVrkaoy0g25p/9Q+52BbcqzFa8=; b=UuCWyMFgUn2UoT7w632Nr3aNfCILMY8J8UrgaR95AMIoW8N1uLGqdsLnO97+Sy0HdWPCz2 yfISfV1pA9Ljn1Gu1pcSKhdnFMCqlarvvDdD0TKNRJvz3MkH0P3IiidwHsOv8MlJpFYFx9 dJlhShnLRLqHqT+00WQnfBXG73mqU9E= 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-443-pYU6K7cEPN6m1aEoMABn2Q-1; Thu, 24 Sep 2020 20:43:40 -0400 X-MC-Unique: pYU6K7cEPN6m1aEoMABn2Q-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F02A710074BF; Fri, 25 Sep 2020 00:43:38 +0000 (UTC) Received: from [10.10.119.140] (ovpn-119-140.rdu2.redhat.com [10.10.119.140]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6694955761; Fri, 25 Sep 2020 00:43:38 +0000 (UTC) Subject: Re: [PATCH 03/16] qapi/expr.py: constrain incoming expression types To: Cleber Rosa , Eduardo Habkost References: <20200922211313.4082880-1-jsnow@redhat.com> <20200922211313.4082880-4-jsnow@redhat.com> <20200923194224.GD3312949@habkost.net> <20200925000507.GE347918@localhost.localdomain> From: John Snow Message-ID: <23bf846d-eb5b-47a9-de64-3294e1eb8188@redhat.com> Date: Thu, 24 Sep 2020 20:43:37 -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: <20200925000507.GE347918@localhost.localdomain> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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=windows-1252; 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 = 2020/09/22 23:02:20 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.199, 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_H5=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: Michael Roth , Markus Armbruster , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/24/20 8:05 PM, Cleber Rosa wrote: > On Wed, Sep 23, 2020 at 03:42:24PM -0400, Eduardo Habkost wrote: >> On Tue, Sep 22, 2020 at 05:13:00PM -0400, John Snow wrote: >>> mypy does not know the types of values stored in Dicts that masquerade >>> as objects. Help the type checker out by constraining the type. >>> >>> Signed-off-by: John Snow >>> --- >>> scripts/qapi/expr.py | 25 ++++++++++++++++++++++--- >>> 1 file changed, 22 insertions(+), 3 deletions(-) >>> >>> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py >>> index 1872a8a3cc..f6b55a87c1 100644 >>> --- a/scripts/qapi/expr.py >>> +++ b/scripts/qapi/expr.py >>> @@ -15,9 +15,17 @@ >>> # See the COPYING file in the top-level directory. >>> >>> import re >>> +from typing import MutableMapping, Optional >>> >>> from .common import c_name >>> from .error import QAPISemError >>> +from .parser import QAPIDoc >>> +from .source import QAPISourceInfo >>> + >>> + >>> +# Expressions in their raw form are JSON-like structures with arbitrary forms. >>> +# Minimally, their top-level form must be a mapping of strings to values. >>> +Expression = MutableMapping[str, object] >>> >>> >>> # Names must be letters, numbers, -, and _. They must start with letter, >>> @@ -280,9 +288,20 @@ def check_event(expr, info): >>> >>> def check_exprs(exprs): >>> for expr_elem in exprs: >>> - expr = expr_elem['expr'] >>> - info = expr_elem['info'] >>> - doc = expr_elem.get('doc') >>> + # Expression >>> + assert isinstance(expr_elem['expr'], dict) >>> + expr: Expression = expr_elem['expr'] >>> + for key in expr.keys(): >>> + assert isinstance(key, str) >> >> mypy doesn't seem to require the key type asserts, on my testing. >> > > Do you mean that mypy actually takes notice of the type assert? And > includes that as source of information for the type check or am I > misinterpreting you? > > BTW, what I understood from this assert is that a more specific > type than the MutableMapping is desirable here. Did I get that > right John? > Yes, we do want a more specific type. We'll get one somewhere in part 5 when parser.py gets a workout. > - Cleber. > mypy takes notice of assert isinstance(x, FooType) because below this line, it is not possible for x to be anything other than a FooType. You can use this to "downcast" types. you can use cast() too, but those are "unsafe", in that they don't actually check. assert *will* check. You can also constrain types by doing a simple: if isinstance(x, FooType): x.FooMethod()