From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C62A0C433E0 for ; Thu, 4 Jun 2020 18:34:53 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 97084206A2 for ; Thu, 4 Jun 2020 18:34:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="K3y+9J2Q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 97084206A2 Authentication-Results: mail.kernel.org; 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]:33654 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jguhY-0001ez-T9 for qemu-devel@archiver.kernel.org; Thu, 04 Jun 2020 14:34:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38446) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jgugm-0000cg-R6 for qemu-devel@nongnu.org; Thu, 04 Jun 2020 14:34:05 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:23223 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jgugl-0008TV-RV for qemu-devel@nongnu.org; Thu, 04 Jun 2020 14:34:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591295642; 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:autocrypt:autocrypt; bh=SOnebtIy5fHs0au7zsz4pKlvOi11nWUNPEULWFtiju8=; b=K3y+9J2QvpOT3aeH+aiVRCbkvq5q4yfXjXuaVNkOGnl8smXY9rjbFRzfbkgvd9DQkpGwdi eRYEPt4LhPVulO9SsvEn3/gm23yfEIBcEI3AApJVhqqAZlhR0MUiRFKbMRS++mMRT++ZUK jV1WC02LJvhk8j3CZv22B/R334Knh5o= 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-157-9sorCv6FNuyKGYhWdAW4_A-1; Thu, 04 Jun 2020 14:34:01 -0400 X-MC-Unique: 9sorCv6FNuyKGYhWdAW4_A-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EF19C18A822A; Thu, 4 Jun 2020 18:33:59 +0000 (UTC) Received: from [10.10.117.188] (ovpn-117-188.rdu2.redhat.com [10.10.117.188]) by smtp.corp.redhat.com (Postfix) with ESMTP id 90342891D3; Thu, 4 Jun 2020 18:33:52 +0000 (UTC) Subject: Re: [PATCH v2 05/16] python/qmp.py: add casts to JSON deserialization To: Kevin Wolf References: <20200602214528.12107-1-jsnow@redhat.com> <20200602214528.12107-6-jsnow@redhat.com> <20200604134944.GG4512@linux.fritz.box> From: John Snow Autocrypt: addr=jsnow@redhat.com; prefer-encrypt=mutual; keydata= mQINBFTKefwBEAChvwqYC6saTzawbih87LqBYq0d5A8jXYXaiFMV/EvMSDqqY4EY6whXliNO IYzhgrPEe7ZmPxbCSe4iMykjhwMh5byIHDoPGDU+FsQty2KXuoxto+ZdrP9gymAgmyqdk3aV vzzmCa3cOppcqKvA0Kqr10UeX/z4OMVV390V+DVWUvzXpda45/Sxup57pk+hyY52wxxjIqef rj8u5BN93s5uCVTus0oiVA6W+iXYzTvVDStMFVqnTxSxlpZoH5RGKvmoWV3uutByQyBPHW2U 1Y6n6iEZ9MlP3hcDqlo0S8jeP03HaD4gOqCuqLceWF5+2WyHzNfylpNMFVi+Hp0H/nSDtCvQ ua7j+6Pt7q5rvqgHvRipkDDVsjqwasuNc3wyoHexrBeLU/iJBuDld5iLy+dHXoYMB3HmjMxj 3K5/8XhGrDx6BDFeO3HIpi3u2z1jniB7RtyVEtdupED6lqsDj0oSz9NxaOFZrS3Jf6z/kHIf h42mM9Sx7+s4c07N2LieUxcfqhFTaa/voRibF4cmkBVUhOD1AKXNfhEsTvmcz9NbUchCkcvA T9119CrsxfVsE7bXiGvdXnzyGLXdsoosjzwacKdOrVaDmN3Uy+SHiQXo6TlkSdV0XH2PUxTM LsBFIO9qXO43Ai6J6iPAP/01l8fuZfpJE0/L/c25yyaND7xA3wARAQABtCpKb2huIFNub3cg KEpvaG4gSHVzdG9uKSA8anNub3dAcmVkaGF0LmNvbT6JAlQEEwECAD4CGwMCHgECF4AFCwkI BwMFFQoJCAsFFgIDAQAWIQT665cRoSz0dYEvGPKIqQZNGDVh6wUCXF392gUJC1Xq3gAKCRCI qQZNGDVh6558D/9pM4pu4njX5aT6uUW3vAmbWLF1jfPxiTQgSHAnm9EBMZED/fsvkzj97clo LN7JKmbYZNgJmR01A7flG45V4iOR/249qAfaVuD+ZzZi1R4jFzr13WS+IEdn0hYp9ITndb7R ezW+HGu6/rP2PnfmDnNowgJu6Dp6IUEabq8SXXwGHXZPuMIrsXJxUdKJdGnh1o2u7271yNO7 J9PEMuMDsgjsdnaGtv7aQ9CECtXvBleAc06pLW2HU10r5wQyBMZGITemJdBhhdzGmbHAL0M6 vKi/bafHRWqfMqOAdDkv3Jg4arl2NCG/uNateR1z5e529+UlB4XVAQT+f5T/YyI65DFTY940 il3aZhA8u788jZEPMXmt94u7uPZbEYp7V0jt68SrTaOgO7NaXsboXFjwEa42Ug5lB5d5/Qdp 1AITUv0NJ51kKwhHL1dEagGeloIsGVQILmpS0MLdtitBHqZLsnJkRvtMaxo47giyBlv2ewmq tIGTlVLxHx9xkc9aVepOuiGlZaZB72c9AvZs9rKaAjgU2UfJHlB/Hr4uSk/1EY0IgMv4vnsG 1sA5gvS7A4T4euu0PqHtn2sZEWDrk5RDbw0yIb53JYdXboLFmFXKzVASfKh2ZVeXRBlQQSJi 3PBR1GzzqORlfryby7mkY857xzCI2NkIkD2eq+HhzFTfFOTdGrkCDQRUynn8ARAAwbhP45BE d/zAMBPV2dk2WwIwKRSKULElP3kXpcuiDWYQob3UODUUqClO+3aXVRndaNmZX9WbzGYexVo3 5j+CVBCGr3DlU8AL9pp3KQ3SJihWcDed1LSmUf8tS+10d6mdGxDqgnd/OWU214isvhgWZtZG MM/Xj7cx5pERIiP+jqu7PT1cibcfcEKhPjYdyV1QnLtKNGrTg/UMKaL+qkWBUI/8uBoa0HLs NH63bXsRtNAG8w6qG7iiueYZUIXKc4IHINUguqYQJVdSe+u8b2N5XNhDSEUhdlqFYraJvX6d TjxMTW5lzVG2KjztfErRNSUmu2gezbw1/CV0ztniOKDA7mkQi6UIUDRh4LxRm5mflfKiCyDQ L6P/jxHBxFv+sIgjuLrfNhIC1p3z9rvCh+idAVJgtHtYl8p6GAVrF+4xQV2zZH45tgmHo2+S JsLPjXZtWVsWANpepXnesyabWtNAV4qQB7/SfC77zZwsVX0OOY2Qc+iohmXo8U7DgXVDgl/R /5Qgfnlv0/3rOdMt6ZPy5LJr8D9LJmcP0RvX98jyoBOf06Q9QtEwJsNLCOCo2LKNL71DNjZr nXEwjUH66CXiRXDbDKprt71BiSTitkFhGGU88XCtrp8R9yArXPf4MN+wNYBjfT7K29gWTzxt 9DYQIvEf69oZD5Z5qHYGp031E90AEQEAAYkCPAQYAQIAJgIbDBYhBPrrlxGhLPR1gS8Y8oip Bk0YNWHrBQJcXf3JBQkLVerNAAoJEIipBk0YNWHrU1AP/1FOK2SBGbyhHa5vDHuf47fgLipC e0/h1E0vdSonzlhPxuZoQ47FjzG9uOhqqQG6/PqtWs/FJIyz8aGG4aV+pSA/9Ko3/2ND8MSY ZflWs7Y8Peg08Ro01GTHFITjEUgHpTpHiT6TNcZB5aZNJ8jqCtW5UlqvXXbVeSTmO70ZiVtc vUJbpvSxYmzhFfZWaXIPcNcKWL1rnmnzs67lDhMLdkYVf91aml/XtyMUlfB8Iaejzud9Ht3r C0pA9MG57pLblX7okEshxAC0+tUdY2vANWFeX0mgqRt1GSuG9XM9H/cKP1czfUV/FgaWo/Ya fM4eMhUAlL/y+/AJxxumPhBXftM4yuiktp2JMezoIMJI9fmhjfWDw7+2jVrx9ze1joLakFD1 rVAoHxVJ7ORfQ4Ni/qWbQm3T6qQkSMt4N/scNsMczibdTPxU7qtwQwIeFOOc3wEwmJ9Qe3ox TODQ0agXiWVj0OXYCHJ6MxTDswtyTGQW+nUHpKBgHGwUaR6d1kr/LK9+5LpOfRlK9VRfEu7D PGNiRkr8Abp8jHsrBqQWfUS1bAf62bq6XUel0kUCtb7qCq024aOczXYWPFpJFX+nhp4d7NeH Edq+wlC13sBSiSHC7T5yssJ+7JPa2ATLlSKhEvBsLe2TsSTTtFlA0nBclqhfJXzimiuge9qU E40lvMWBuQINBFTKimUBEADDbJ+pQ5M4QBMWkaWImRj7c598xIZ37oKM6rGaSnuB1SVb7YCr Ci2MTwQcrQscA2jm80O8VFqWk+/XsEp62dty47GVwSfdGje/3zv3VTH2KhOCKOq3oPP5ZXWY rz2d2WnTvx++o6lU7HLHDEC3NGLYNLkL1lyVxLhnhvcMxkf1EGA1DboEcMgnJrNB1pGP27ww cSfvdyPGseV+qZZa8kuViDga1oxmnYDxFKMGLxrClqHrRt8geQL1Wj5KFM5hFtGTK4da5lPn wGNd6/CINMeCT2AWZY5ySz7/tSZe5F22vPvVZGoPgQicYWdNc3ap7+7IKP86JNjmec/9RJcz jvrYjJdiqBVldXou72CtDydKVLVSKv8c2wBDJghYZitfYIaL8cTvQfUHRYTfo0n5KKSec8Vo vjDuxmdbOUBA+SkRxqmneP5OxGoZ92VusrwWCjry8HRsNdR+2T+ClDCO6Wpihu4V3CPkQwTy eCuMHPAT0ka5paTwLrnZIxsdfnjUa96T10vzmQgAxpbbiaLvgKJ8+76OPdDnhddyxd2ldYfw RkF5PEGg3mqZnYKNNBtwjvX49SAvgETQvLzQ8IKVgZS0m4z9qHHvtc1BsQnFfe+LJOFjzZr7 CrDNJMqk1JTHYsSi2JcN3vY32WMezXSQ0TzeMK4kdnclSQyp/h23GWod5QARAQABiQRbBBgB AgAmAhsCFiEE+uuXEaEs9HWBLxjyiKkGTRg1YesFAlxd/coFCQtV2mQCKcFdIAQZAQIABgUC VMqKZQAKCRB974EGqvw5DiJoEACLmuiRq9ifvOh5DyBFwRS7gvA14DsGQngmC57EzV0EFcfM XVi1jX5OtwUyUe0Az5r6lHyyHDsDsIpLKBlWrYCeLpUhRR3oy181T7UNxvujGFeTkzvLAOo6 Hs3b8Wv9ARg+7acRYkQRNY7k0GIJ6YZz149tRyRKAy/vSjsaB9Lt0NOd1wf2EQMKwRVELwJD y0AazGn+0PRP7Bua2YbtxaBmhBBDb2tPpwn8U9xdckB4Vlft9lcWNsC/18Gi9bpjd9FSbdH/ sOUI+3ToWYENeoT4IP09wn6EkgWaJS3nAUN/MOycNej2i4Yhy2wDDSKyTAnVkSSSoXk+tK91 HfqtokbDanB8daP+K5LgoiWHzjfWzsxA2jKisI4YCGjrYQzTyGOT6P6u6SEeoEx10865B/zc 8/vN50kncdjYz2naacIDEKQNZlnGLsGkpCbfmfdi3Zg4vuWKNdWr0wGUzDUcpqW0y/lUXna+ 6uyQShX5e4JD2UPuf9WAQ9HtgSAkaDd4O1I2J41sleePzZOVB3DmYgy+ECRJJ5nw3ihdxpgc y/v3lfcJaqiyCv0PF+K/gSOvwhH7CbVqARmptT7yhhxqFdaYWo2Z2ksuKyoKSRMFCXQY5oac uTmyPIT4STFyUQFeqSCWDum/NFNoSKhmItw2Td+4VSJHShRVbg39KNFPZ7mXYAkQiKkGTRg1 YesWJA/+PV3qDUtPNEGwjVvjQqHSbrBy94tu6gJvPHgGPtRDYvxnCaJsmgiC0pGB2KFRsnfl 2zBNBEWF/XwsI081jQE5UO60GKmHTputChLXpVobyuc+lroG2YhknXRBAV969SLnZR4BS/1s Gi046gOXfaKYatve8BiZr5it5Foq3FMPDNgZMit1H9Dk8rkKFfDMRf8EGS/Z+TmyEsIf99H7 TH3n7lco8qO81fSFwkh4pvo2kWRFYTC5vsIVQ+GqVUp+W1DZJHxX8LwWuF1AzUt4MUTtNAvy TXl5EgsmoY9mpNNL7ZnW65oG63nEP5KNiybvuQJzXVxR8eqzOh2Mod4nHg3PE7UCd3DvLNsn GXFRo44WyT/G2lArBtjpkut7bDm0i1nENABy2UgS+1QvdmgNu6aEZxdNthwRjUhuuvCCDMA4 rCDQYyakH2tJNQgkXkeLodBKF4bHiBbuwj0E39S9wmGgg+q4OTnAO/yhQGknle7a7G5xHBwE i0HjnLoJP5jDcoMTabZTIazXmJz3pKM11HYJ5/ZsTIf3ZRJJKIvXJpbmcAPVwTZII6XxiJdh RSSX4Mvd5pL/+5WI6NTdW6DMfigTtdd85fe6PwBNVJL2ZvBfsBJZ5rxg1TOH3KLsYBqBTgW2 glQofxhkJhDEcvjLhe3Y2BlbCWKOmvM8XS9TRt0OwUs= Message-ID: <15327daf-12de-ddaf-a829-dae9a0a8d36b@redhat.com> Date: Thu, 4 Jun 2020 14:33:51 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200604134944.GG4512@linux.fritz.box> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.120; envelope-from=jsnow@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/04 13:58:37 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: Eduardo Habkost , qemu-block@nongnu.org, qemu-devel@nongnu.org, Max Reitz , Cleber Rosa , philmd@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 6/4/20 9:49 AM, Kevin Wolf wrote: > Am 02.06.2020 um 23:45 hat John Snow geschrieben: >> mypy and python type hints are not powerful enough to properly describe >> JSON messages in Python 3.6. The best we can do, generally, is describe >> them as Dict[str, Any]. >> >> Add casts to coerce this type for static analysis; but do NOT enforce >> this type at runtime in any way. >> >> Note: Python 3.8 adds a TypedDict construct which allows for the >> description of more arbitrary Dictionary shapes. There is a third-party >> module, "Pydantic", which is compatible with 3.6 that can be used >> instead of the JSON library that parses JSON messages to fully-typed >> Python objects, and may be preferable in some cases. >> >> (That is well beyond the scope of this commit or series.) >> >> Signed-off-by: John Snow >> --- >> python/qemu/qmp.py | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py >> index ef3c919b76c..5f3558e3066 100644 >> --- a/python/qemu/qmp.py >> +++ b/python/qemu/qmp.py >> @@ -13,6 +13,7 @@ >> import logging >> from typing import ( >> Any, >> + cast, >> Dict, >> Optional, >> TextIO, >> @@ -130,7 +131,10 @@ def __json_read(self, only_event=False): >> data = self.__sockfile.readline() >> if not data: >> return None >> - resp = json.loads(data) >> + # By definition, any JSON received from QMP is a QMPMessage, >> + # and we are asserting only at static analysis time that it >> + # has a particular shape. >> + resp = cast(QMPMessage, json.loads(data)) > > Instead of casting, you can just specify the variable type: > > resp: QMPMessage = json.loads(data) > > I don't think that json.loads() will actually return something other > than Any anytime soon, but it's generally nicer to avoid casts and if it > eventually does change, we'll get the type check instead of silencing > it. > Nice, that works with --strict too. Done. >> if 'event' in resp: >> self.logger.debug("<<< %s", resp) >> self.__events.append(resp) >> @@ -262,7 +266,7 @@ def command(self, cmd, **kwds): >> ret = self.cmd(cmd, kwds) >> if 'error' in ret: >> raise QMPResponseError(ret) >> - return ret['return'] >> + return cast(QMPReturnValue, ret['return']) > > This one can't be easily avoided, though. > Sadly not -- we could conceivably make use of e.g. pydantic to create arbitrarily nuanced/strict structure definitions that are actually validated at runtime, but I will save that for a future series. --js