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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 9C9CBC433ED for ; Tue, 27 Apr 2021 08:45:00 +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 1080C6113D for ; Tue, 27 Apr 2021 08:45:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1080C6113D 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]:51404 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lbJL0-0006B9-TF for qemu-devel@archiver.kernel.org; Tue, 27 Apr 2021 04:44:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44248) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lbJK1-0005Ja-VN for qemu-devel@nongnu.org; Tue, 27 Apr 2021 04:43:58 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:42116) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lbJJu-0002Uh-MN for qemu-devel@nongnu.org; Tue, 27 Apr 2021 04:43:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619513024; 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=yZLO0Wtr0PDuJBCDRkoSUCiFoeGoG7T+Dy1+JuGVUcU=; b=ciSRsgT/oom/6hiYR43akNobNNDG/H5oH3nlWRa171uDftuAZG4OxQoFRTLEvRo2CzO/cs 782OY8kSlQn+RfbSUN2zr1CGry4lPTqIH58oulCxS/cUjoGIe4ELcRA6+DWr/ljm4hidTU Z8fVF8YoQE6V6Syj9snn+egGszjICNs= 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-160-X4i5GjZiOXOUyk7hZB_ylg-1; Tue, 27 Apr 2021 04:43:40 -0400 X-MC-Unique: X4i5GjZiOXOUyk7hZB_ylg-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 D6DB7107ACCD; Tue, 27 Apr 2021 08:43:39 +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 A7D416A035; Tue, 27 Apr 2021 08:43:39 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3A51F113525D; Tue, 27 Apr 2021 10:43:38 +0200 (CEST) From: Markus Armbruster To: John Snow Subject: Re: [PATCH 12/22] qapi/parser: add type hint annotations References: <20210422030720.3685766-1-jsnow@redhat.com> <20210422030720.3685766-13-jsnow@redhat.com> <87zgxm5yrp.fsf@dusky.pond.sub.org> <07ad14a5-a1bb-691f-cdc1-93ef82b28e77@redhat.com> Date: Tue, 27 Apr 2021 10:43:38 +0200 In-Reply-To: <07ad14a5-a1bb-691f-cdc1-93ef82b28e77@redhat.com> (John Snow's message of "Mon, 26 Apr 2021 19:55:15 -0400") Message-ID: <87tuns2k3p.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 2.79 on 10.5.11.13 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=170.10.133.124; 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=-0.219, 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 4/25/21 8:34 AM, Markus Armbruster wrote: >> value: object isn't wrong, but why not _ExprValue? >> > > Updated excuse: > > because all the way back outside in _parse, we know that: > > 1. expr is a dict (because of get_expr(False)) > 2. expr['pragma'] is also a dict, because we explicitly check it there. Yes: pragma = expr['pragma'] --> if not isinstance(pragma, dict): --> raise QAPISemError( --> info, "value of 'pragma' must be an object") for name, value in pragma.items(): self._pragma(name, value, info) > 3. We iterate over the keys; all we know so far is that the values are > ... something. Actually, *we* know more about the values. get_expr() returns a tree whose inner nodes are dict or list, and whose leaves are str or bool. Therefore, the values are dict, list, str, or bool. It's *mypy* that doesn't know, because it lacks recursive types. I know that you're prbably using "we" in the sense of "the toolchain". I'm annoying you with the difference between "the toolchain" and "we (you, me, and other humans) because I'm concerned about us humans dumbing ourselves down to mypy's level of understanding. To be honest, I'm less and less sure typing these trees without the necessary typing tools is worth the bother. The notational overhead it more oppressive than elsewhere, and yet the typing remains weak. The result fails to satisfy, and that's a constant source of discussions (between us as well as just in my head) on how to best mitigate. > 4. _pragma()'s job is to validate the type(s) anyway. _pragma() can safely assume @value is dict, list, str, or bool. It just happens not to rely on this assumption. > More or less, the _ExprValue type union isn't remembered here -- even > though it was once upon a time something returned by get_expr, it > happened in a nested call that is now opaque to mypy in this context. Understand. > So, it's some combination of "That's all we know about it" and "It > happens to be exactly sufficient for this function to operate." I can accept "it's all mypy can figure out by itself, and it's good enough to get the static checking we want".