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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]:47500 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lk7re-0000Bc-Oy for qemu-devel@archiver.kernel.org; Fri, 21 May 2021 12:19:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48472) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lk7qs-0007mA-SQ for qemu-devel@nongnu.org; Fri, 21 May 2021 12:18:19 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:36395) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lk7qp-000802-Ps for qemu-devel@nongnu.org; Fri, 21 May 2021 12:18:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1621613894; 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=rMxR+jJDZdbhXyY8pGif7PXes1jFcto51rRbszEPFzo=; b=cHXh3pA1Jw65oxHTA9cBhuc25LHH/Me5qerwBZZb+NnQCSS3yTFtSxQsG4zRvmOZ/pJmLw 3ApprP2xW6Eh8RrgBZ9v5coArCSoQiyqY7u63Id8J/v6oJVTZ1Rt8+BY1DRSLaA5hTywWD ydmg3dKgk6S6WJf4Ru8uP7rfE5O4h64= 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-596-awCay74cNVq7EzURbK5mPg-1; Fri, 21 May 2021 12:18:11 -0400 X-MC-Unique: awCay74cNVq7EzURbK5mPg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8C23A6D4E3 for ; Fri, 21 May 2021 16:18:10 +0000 (UTC) Received: from [10.10.117.64] (ovpn-117-64.rdu2.redhat.com [10.10.117.64]) by smtp.corp.redhat.com (Postfix) with ESMTP id 141345D9E3; Fri, 21 May 2021 16:18:03 +0000 (UTC) Subject: Re: [PATCH v3 3/9] qapi: start building an 'if' predicate tree To: Markus Armbruster References: <20210429134032.1125111-1-marcandre.lureau@redhat.com> <20210429134032.1125111-4-marcandre.lureau@redhat.com> <5d0a776e-e597-6996-c407-cd2d91883eac@redhat.com> <87eee02ldl.fsf@dusky.pond.sub.org> From: John Snow Message-ID: <12434341-9054-8c35-e8a4-59087548b59e@redhat.com> Date: Fri, 21 May 2021 12:18:03 -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: <87eee02ldl.fsf@dusky.pond.sub.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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: 8bit 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: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.374, 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: marcandre.lureau@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 5/21/21 10:48 AM, Markus Armbruster wrote: > Beware, I'm skimming, not really reviewing. > > John Snow writes: > >> On 4/29/21 9:40 AM, marcandre.lureau@redhat.com wrote: >>> From: Marc-André Lureau >>> The following patches are going to express schema 'if' conditions in >>> a >>> target language agnostic way. For that, let's start building a predicate >>> tree of the configuration options. >>> This intermediary steps still uses C-preprocessor expressions as >>> the predicates: >>> "if: [STR, ..]" is translated to a "IfCond -> IfAll -> >>> [IfOption, ..]" tree, which will generate "#if STR && .." C code. >>> Once the boolean operation tree nodes are introduced, the 'if' >>> expressions will be converted to replace the C syntax (no more >>> !defined(), &&, ...) and based only on option identifiers. >>> For now, the condition tree will be less expressive than a full C >>> macro >>> expression as it will only support these operations: 'all', 'any' and >>> 'not', the only ones needed so far. >>> Signed-off-by: Marc-André Lureau >>> --- >>> docs/sphinx/qapidoc.py | 6 +-- >>> scripts/qapi/common.py | 54 +++++++++++++++++++++++- >>> scripts/qapi/schema.py | 42 ++++++++++++------- >>> tests/qapi-schema/doc-good.out | 12 +++--- >>> tests/qapi-schema/qapi-schema-test.out | 58 +++++++++++++------------- >>> 5 files changed, 116 insertions(+), 56 deletions(-) >>> diff --git a/docs/sphinx/qapidoc.py b/docs/sphinx/qapidoc.py >>> index b737949007..a93f3f1c4d 100644 >>> --- a/docs/sphinx/qapidoc.py >>> +++ b/docs/sphinx/qapidoc.py >>> @@ -112,12 +112,10 @@ def _make_section(self, title): >>> def _nodes_for_ifcond(self, ifcond, with_if=True): >>> """Return list of Text, literal nodes for the ifcond >>> - Return a list which gives text like ' (If: cond1, cond2, >>> cond3)', where >>> - the conditions are in literal-text and the commas are not. >>> + Return a list which gives text like ' (If: condition)'. >>> If with_if is False, we don't return the "(If: " and ")". >>> """ >>> - condlist = intersperse([nodes.literal('', c) for c in ifcond.ifcond], >>> - nodes.Text(', ')) >> >> was this the last user of intersperse? >> >> mm, no, there's one more. >> >>> + condlist = [nodes.literal('', ifcond.gen_doc())] >>> if not with_if: >>> return condlist >>> diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py >>> index b7f475a160..59a7ee2f32 100644 >>> --- a/scripts/qapi/common.py >>> +++ b/scripts/qapi/common.py >>> @@ -11,8 +11,9 @@ >>> # This work is licensed under the terms of the GNU GPL, version 2. >>> # See the COPYING file in the top-level directory. >>> +from abc import ABC, abstractmethod >>> import re >>> -from typing import Optional >>> +from typing import Optional, Sequence >>> >>> #: Magic string that gets removed along with all space to its right. >>> @@ -192,3 +193,54 @@ def guardend(name: str) -> str: >>> #endif /* %(name)s */ >>> ''', >>> name=c_fname(name).upper()) >>> + >>> + >>> +class IfPredicate(ABC): >>> + @abstractmethod >>> + def cgen(self) -> str: >> >> Like the review to patch 2, I'm not sure we want to bake cgen stuff >> directly into this class. Are you going to have cgen() and rustgen() >> methods all here? >> >>> + pass >>> + >> >> I think you want raise NotImplementedError to specify a function that >> the inheriting class MUST implement. Otherwise, there's little value >> to allow a child class to call super() on a method that doesn't have a >> default implementation. >> >> You *could* drop the (ABC) and the @abstractmethod decorators if you do so. >> >> Matters of taste and style. > > We're not coding a library for use by thousands of people. If we did, > then complicating the code to guard against misuse could be a win. But > we don't. > > schema.py is full of methods that pass. Maybe some of them need to be > overriden by any conceivable subtype. Who cares? The subtypes either > work or they don't. I prefer > > def frobnicate: > pass > > to > > def frobnicate: > raise NotImplementedError > > One, pass is easier on the eyes. Two, a subtype's .frobnicate() can > blindly call super().frobnicate(). > "pass" here operates as a syntactic sugar for "return None" which has implications on the return type. It's short, but wrong. raise NotImplementedError means something different semantically. To me, pass is *NOT* easier on the eyes, it is misleading. It is idiomatic to use NotImplementedError if it is not acceptable for a default implementation to return None. I understand perfectly well the desire to keep things simple, but what is actually "simple" depends on the expectations of the programmer. I err towards idiomatic Python. > I don't see a need to fuzz around with module abc, either. Let's stick > to the stupidest solution that could possibly work. > > [...] >