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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 53CF0C433B4 for ; Tue, 27 Apr 2021 12:34:09 +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 8A50A61059 for ; Tue, 27 Apr 2021 12:34:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8A50A61059 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]:52194 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lbMul-0002AO-CD for qemu-devel@archiver.kernel.org; Tue, 27 Apr 2021 08:34:07 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38826) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lbMry-0000sm-3J for qemu-devel@nongnu.org; Tue, 27 Apr 2021 08:31:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:37707) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lbMrl-0001rr-UV for qemu-devel@nongnu.org; Tue, 27 Apr 2021 08:31:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619526654; 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: in-reply-to:in-reply-to:references:references; bh=9e2VX+il8FwP+r9BiXa3DgdGt8IuJHCzzfxWacj9I3w=; b=Ap7nYMa3l5W5W+EnOaVzLzBypoMGMVJd74zRs0N2PJzC/dphOJE17ECFc6j94p85mX6/Bp VxeZsit114oxEWtK451ifHw0uORCyKBKx1UnrA9Oar/U1eJRQ+o3Rings3zAbnyrdReRNN LGYXaUSaZ3gh4WcNYF1Ha/lwiUTgwVE= 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-183-hk_2g_mJOYmIgaNw2XP6GQ-1; Tue, 27 Apr 2021 08:30:52 -0400 X-MC-Unique: hk_2g_mJOYmIgaNw2XP6GQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 92DEBA40C4; Tue, 27 Apr 2021 12:30:51 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-114-17.ams2.redhat.com [10.36.114.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4AEC819714; Tue, 27 Apr 2021 12:30:51 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id CF29B113525D; Tue, 27 Apr 2021 14:30:49 +0200 (CEST) From: Markus Armbruster To: John Snow Subject: Re: [PATCH 05/22] qapi/parser: Assert lexer value is a string References: <20210422030720.3685766-1-jsnow@redhat.com> <20210422030720.3685766-6-jsnow@redhat.com> <87k0os9j4t.fsf@dusky.pond.sub.org> Date: Tue, 27 Apr 2021 14:30:49 +0200 In-Reply-To: (John Snow's message of "Mon, 26 Apr 2021 13:43:29 -0400") Message-ID: <874kfrykna.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.218, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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 , Cleber Rosa , qemu-devel@nongnu.org, Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" John Snow writes: > On 4/24/21 4:33 AM, Markus Armbruster wrote: >> The second operand of assert provides no additional information. Please >> drop it. > > I don't agree with "no additional information", strictly. > > I left you a comment on gitlab before you started reviewing on-list. > What I wrote there: > > "Markus: I know you're not a fan of these, but I wanted a suggestion on > how to explain why this must be true in case it wasn't obvious to > someone else in the future." But the second operand doesn't explain anything. Look: diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py index f519518075e..c75434e75a5 100644 --- a/scripts/qapi/parser.py +++ b/scripts/qapi/parser.py @@ -303,6 +303,7 @@ def get_doc(self, info): cur_doc = QAPIDoc(self, info) self.accept(False) while self.tok == '#': + assert isinstance(self.val, str), "Expected str value" if self.val.startswith('##'): # End of doc comment if self.val != '##': The second operand paraphrases the first one in prose rather than code. An actual *explanation* would instead tell me why the first operand must be true. To do that, I'd point to self.accept()'s postcondition. Which (informally) is self.tok in ('#', '{', ... ) and self.tok == '#' implies self.val is a str and self.tok == '{' implies self.val is None ... I believe this is required working knowledge for understanding the parser. Your PATCH 16 puts it in a doc string, so readers don't have to extract it from code. Makes sense. It's not going to fit into a workable second operand here, I'm afraid. I assume you need this assertion for mypy. If yes, let's get the job done with minimal fuss. If no, please drop the assertion entirely.