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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43836 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lPq1z-0007VN-Pq for qemu-devel@archiver.kernel.org; Fri, 26 Mar 2021 13:13:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39910) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lPq16-0006pb-LV for qemu-devel@nongnu.org; Fri, 26 Mar 2021 13:13:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:36408) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lPq13-0000qR-Bs for qemu-devel@nongnu.org; Fri, 26 Mar 2021 13:12:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616778775; 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=oOpqHBScIqijqhWe5Gvq8Z+6UJ3bSwaV+DMA47a17yI=; b=OY50TECD1g48ggJ/+Ecmj3IkJm1ENgnGaXDUUzSaqEeG+wLibsZ6ziS7q8zDSEh77abdx6 QPYKWFgqrFwAL80sZPnVWA6XhvvLsp6fw4E2PZ+qMKxoLCm4TKaxxC38wd0SpQD7X39Bj/ XvwRPFcIeHIDGj7bDL4xNKyvEnkfQVk= 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-186-KRx9uwqcNQO9EW9cglmMJw-1; Fri, 26 Mar 2021 13:12:51 -0400 X-MC-Unique: KRx9uwqcNQO9EW9cglmMJw-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 B0251107ACCA; Fri, 26 Mar 2021 17:12:50 +0000 (UTC) Received: from [10.10.117.181] (ovpn-117-181.rdu2.redhat.com [10.10.117.181]) by smtp.corp.redhat.com (Postfix) with ESMTP id 237FF5D6DC; Fri, 26 Mar 2021 17:12:50 +0000 (UTC) Subject: Re: [PATCH v4 05/19] qapi/expr.py: constrain incoming expression types To: Markus Armbruster References: <20210325060356.4040114-1-jsnow@redhat.com> <20210325060356.4040114-6-jsnow@redhat.com> <871rc3tjlt.fsf@dusky.pond.sub.org> <87sg4ia2wz.fsf@dusky.pond.sub.org> From: John Snow Message-ID: <75da83c0-5d57-1070-a3d3-3f683563b6a1@redhat.com> Date: Fri, 26 Mar 2021 13:12:49 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87sg4ia2wz.fsf@dusky.pond.sub.org> 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=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit 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=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, 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: Michael Roth , qemu-devel@nongnu.org, Eduardo Habkost , Cleber Rosa Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/26/21 1:40 AM, Markus Armbruster wrote: > John Snow writes: > >> On 3/25/21 10:04 AM, Markus Armbruster wrote: >>> John Snow writes: >>> >>>> 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 | 26 +++++++++++++++++++++++--- >>>> 1 file changed, 23 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py >>>> index b4bbcd54c0..b75c85c160 100644 >>>> --- a/scripts/qapi/expr.py >>>> +++ b/scripts/qapi/expr.py >>>> @@ -15,9 +15,18 @@ >>>> # See the COPYING file in the top-level directory. >>>> >>>> import re >>>> +from typing import Dict, Optional >>>> >>>> from .common import c_name >>>> from .error import QAPISemError >>>> +from .parser import QAPIDoc >>>> +from .source import QAPISourceInfo >>>> + >>>> + >>>> +# Deserialized JSON objects as returned by the parser; >>>> +# The values of this mapping are not necessary to exhaustively type >>> >>> Not necessary and also not practical with current mypy. Correct? >> >> Neither necessary nor practical. Typing as 'object' guarantees that >> these values will never be used in a manner not supported by all python >> objects. Mypy does not complain, so we know that we don't misuse the type. >> >> This is helpful for proving the validity of the expr.py validator >> itself: we know that we are not forgetting to perform type narrowing and >> using the value contained therein inappropriately. >> >> Adding a more exhaustive typing here is impractical (for reasons we >> learned during introspect.py), but also provides no benefit to the >> static analysis here anyway. >> >> (None of the functions written here *assume* the shape of the structure, >> so there are no functions that benefit from having a more laboriously >> specified type.) >> >> If the comment needs more work, suggest away -- I tried to follow our >> last discussion here as best as I was able. > > "Needs more work" sounds like "inadequate", which isn't the case. > > The comment focuses on what we need from mypy here. We may or may not > want to hint at the other aspect: what mypy can provide. > >>>> +# here, because the purpose of this module is to interrogate that type. >>>> +_JSONObject = Dict[str, object] > [...] > > If we want to, maybe: > > # Deserialized JSON objects as returned by the parser. > # The values of this mapping are not necessary to exhaustively type > # here (and also not practical as long as mypy lacks recursive > # types), because the purpose of this module is to interrogate that > # type. > > Thoughts? > If it occurs to you to want the extra explanation, I won't say no to it. I will fold it in. --js