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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,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 83FCEC433B4 for ; Tue, 27 Apr 2021 07:17:54 +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 F0339613A9 for ; Tue, 27 Apr 2021 07:17:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F0339613A9 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]:33918 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lbHyi-00069D-Uk for qemu-devel@archiver.kernel.org; Tue, 27 Apr 2021 03:17:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52806) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lbHwR-0004nv-RE for qemu-devel@nongnu.org; Tue, 27 Apr 2021 03:15:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:31701) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lbHwQ-00073R-0E for qemu-devel@nongnu.org; Tue, 27 Apr 2021 03:15:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619507729; 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=wyNvWj0G20C9NEJvhstHott1UUpwlbd/aWttfjSUHqo=; b=DJWioaIJL2UI/Rp9AiGVzdusEnF7EHKNcgcNP2m3A7GDt9JUyUFZS37H7mFh2+p+B+c2G7 4byAc5/0zS501oojlcdCB7P4q8FkihxpdGBCcCY9SOrQ/437zf21q1QZG3rFYhFSJVqTtu aazbf/EMpqeFomAGMlvLUOTY/r8IjCg= 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-523-X3A8dvKEPEGfnlWFKzmEKw-1; Tue, 27 Apr 2021 03:15:25 -0400 X-MC-Unique: X3A8dvKEPEGfnlWFKzmEKw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 79C5F801AB6; Tue, 27 Apr 2021 07:15:24 +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 242CB76C1D; Tue, 27 Apr 2021 07:15:24 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id A3469113525D; Tue, 27 Apr 2021 09:15:22 +0200 (CEST) From: Markus Armbruster To: John Snow Subject: Re: [PATCH 11/22] qapi/parser: Rework _check_pragma_list_of_str as a TypeGuard References: <20210422030720.3685766-1-jsnow@redhat.com> <20210422030720.3685766-12-jsnow@redhat.com> <871ray7dfd.fsf@dusky.pond.sub.org> <83aa318c-1a54-35a2-2cec-8d4503392c2f@redhat.com> Date: Tue, 27 Apr 2021 09:15:22 +0200 In-Reply-To: <83aa318c-1a54-35a2-2cec-8d4503392c2f@redhat.com> (John Snow's message of "Mon, 26 Apr 2021 19:48:10 -0400") Message-ID: <87czug6vw5.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 10.5.11.11 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=-0.219, 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 8:32 AM, Markus Armbruster wrote: >> John Snow writes: >> >>> TypeGuards wont exist in Python proper until 3.10. Ah well. We can hack >>> up our own by declaring this function to return the type we claim it >>> checks for and using this to safely downcast object -> List[str]. >>> >>> In so doing, I bring this function in-line under _pragma so it can use >>> the 'info' object in its closure. Having done this, _pragma also now >>> no longer needs to take a 'self' parameter, so drop it. >>> >>> Rename it to just _check(), to help us out with the line-length -- and >>> now that it's contained within _pragma, it is contextually easier to see >>> how it's used anyway -- especially with types. >>> >>> Signed-off-by: John Snow >>> >>> --- >>> >>> I left (name, value) as args to avoid creating a fully magic "macro", >>> though, I thought this was too weird: >>> >>> info.pragma.foobar = _check() >>> >>> and it looked more reasonable as: >>> >>> info.pragma.foobar = _check(name, value) >>> >>> Signed-off-by: John Snow >>> --- >>> scripts/qapi/parser.py | 26 +++++++++++++------------- >>> 1 file changed, 13 insertions(+), 13 deletions(-) >>> >>> diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py >>> index 16fd36f8391..d02a134aae9 100644 >>> --- a/scripts/qapi/parser.py >>> +++ b/scripts/qapi/parser.py >>> @@ -17,6 +17,7 @@ >>> from collections import OrderedDict >>> import os >>> import re >>> +from typing import List >>> >>> from .common import match_nofail >>> from .error import QAPISemError, QAPISourceError >>> @@ -151,28 +152,27 @@ def _include(include, info, incl_fname, previously_included): >>> ) from err >>> >>> @staticmethod >>> - def _check_pragma_list_of_str(name, value, info): >>> - if (not isinstance(value, list) >>> - or any([not isinstance(elt, str) for elt in value])): >>> - raise QAPISemError( >>> - info, >>> - "pragma %s must be a list of strings" % name) >>> + def _pragma(name, value, info): >>> + >>> + def _check(name, value) -> List[str]: >>> + if (not isinstance(value, list) or >>> + any([not isinstance(elt, str) for elt in value])): >>> + raise QAPISemError( >>> + info, >>> + "pragma %s must be a list of strings" % name) >>> + return value >>> >>> - def _pragma(self, name, value, info): >>> if name == 'doc-required': >>> if not isinstance(value, bool): >>> raise QAPISemError(info, >>> "pragma 'doc-required' must be boolean") >>> info.pragma.doc_required = value >>> elif name == 'command-name-exceptions': >>> - self._check_pragma_list_of_str(name, value, info) >>> - info.pragma.command_name_exceptions = value >>> + info.pragma.command_name_exceptions = _check(name, value) >>> elif name == 'command-returns-exceptions': >>> - self._check_pragma_list_of_str(name, value, info) >>> - info.pragma.command_returns_exceptions = value >>> + info.pragma.command_returns_exceptions = _check(name, value) >>> elif name == 'member-name-exceptions': >>> - self._check_pragma_list_of_str(name, value, info) >>> - info.pragma.member_name_exceptions = value >>> + info.pragma.member_name_exceptions = _check(name, value) >>> else: >>> raise QAPISemError(info, "unknown pragma '%s'" % name) >> >> While I appreciate the terseness, I'm not sure I like the generic name >> _check() for checking one of two special cases, namely "list of string". >> The other case being "boolean". We could acquire more cases later. >> > > Yeah, sorry, just trying to make the line fit ... I understand! > The important thing is that we need to make sure this routine returns > some known type. It's just that the block down here has very long lines. > > Recommendations? Moving the helper into _pragma() lets us drop shorten its name. Still too long to fit the line: info.pragma.command_returns_exceptions = check_list_str(name, value) We could break the line in the argument list: info.pragma.command_returns_exceptions = check_list_str(name, value) or info.pragma.command_returns_exceptions = check_list_str( name, value) Not exactly pretty. We could shorten the assignment's target: pragma.command_returns_exceptions = check_list_str(name, value) with pragma.info = pragma before the conditional. I'm not too fond of creating aliases, but this one looks decent to me. What do you think?