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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]:46096 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kLoxB-0004Kh-7E for qemu-devel@archiver.kernel.org; Fri, 25 Sep 2020 10:44:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48820) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kLowB-0003I9-Vn for qemu-devel@nongnu.org; Fri, 25 Sep 2020 10:43:04 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:33081) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kLow9-0007f4-Bv for qemu-devel@nongnu.org; Fri, 25 Sep 2020 10:43:03 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601044980; 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=EAKCe/q35Gh1oXvYmoZR9CaYu4M+JPCtD+Ql3PdHoh4=; b=VgcN/c+Wnhm1czpD0rZfQavwRN/VwHeJOo1xJMwcA4s6evf4huyIkfPB5kXih+H7tBJ8Qj fsp25hDka6l2UAfPlna/8OdkZkIb0mxa1HzPMsVHU5z4QNwUuJexkXm7dhgAbfPC4p8LT+ N2GyM80X74PeMufp7fcNzROnbx0g6xU= 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-273-Jh8bfQUjPl-b7JvODO-RJA-1; Fri, 25 Sep 2020 10:42:58 -0400 X-MC-Unique: Jh8bfQUjPl-b7JvODO-RJA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 016EB802EA3; Fri, 25 Sep 2020 14:42:57 +0000 (UTC) Received: from [10.10.119.140] (ovpn-119-140.rdu2.redhat.com [10.10.119.140]) by smtp.corp.redhat.com (Postfix) with ESMTP id BF57F5576F; Fri, 25 Sep 2020 14:42:55 +0000 (UTC) Subject: Re: [PATCH v2 09/38] qapi/common.py: Add indent manager To: Markus Armbruster References: <20200922210101.4081073-1-jsnow@redhat.com> <20200922210101.4081073-10-jsnow@redhat.com> <20200922222232.GK2044576@habkost.net> <87sgb6t6p1.fsf@dusky.pond.sub.org> From: John Snow Message-ID: Date: Fri, 25 Sep 2020 10:42:54 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <87sgb6t6p1.fsf@dusky.pond.sub.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/25 02:48:20 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.199, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.238, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=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: Peter Maydell , Eduardo Habkost , qemu-devel@nongnu.org, Michael Roth , Cleber Rosa , =?UTF-8?Q?Alex_Benn=c3=a9e?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/25/20 7:51 AM, Markus Armbruster wrote: > John Snow writes: > >> On 9/22/20 6:22 PM, Eduardo Habkost wrote: >>> On Tue, Sep 22, 2020 at 05:00:32PM -0400, John Snow wrote: >>>> Code style tools really dislike the use of global keywords, because it >>>> generally involves re-binding the name at runtime which can have strange >>>> effects depending on when and how that global name is referenced in >>>> other modules. >>>> >>>> Make a little indent level manager instead. >>>> >>>> Signed-off-by: John Snow >>>> --- >>>> scripts/qapi/common.py | 51 +++++++++++++++++++++++++++++------------- >>>> scripts/qapi/visit.py | 7 +++--- >>>> 2 files changed, 38 insertions(+), 20 deletions(-) >>>> >>>> diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py >>>> index cee63eb95c..e0c5871b10 100644 >>>> --- a/scripts/qapi/common.py >>>> +++ b/scripts/qapi/common.py >>>> @@ -93,33 +93,52 @@ def c_name(name, protect=True): >>>> pointer_suffix = ' *' + eatspace >>>> >>>> -def genindent(count): >>>> - ret = '' >>>> - for _ in range(count): >>>> - ret += ' ' >>>> - return ret >>>> +class Indentation: >>>> + """ >>>> + Indentation level management. >>>> + :param initial: Initial number of spaces, default 0. >>>> + """ >>>> + def __init__(self, initial: int = 0) -> None: >>>> + self._level = initial >>>> -indent_level = 0 >>>> + def __int__(self) -> int: >>>> + return self._level >>>> + def __repr__(self) -> str: >>>> + return "{}({:d})".format(type(self).__name__, self._level) >>>> -def push_indent(indent_amount=4): >>>> - global indent_level >>>> - indent_level += indent_amount >>>> + def __str__(self) -> str: >>>> + """Return the current indentation as a string of spaces.""" >>>> + return ' ' * self._level >>>> + def __bool__(self) -> bool: >>>> + """True when there is a non-zero indentation.""" >>>> + return bool(self._level) >>>> -def pop_indent(indent_amount=4): >>>> - global indent_level >>>> - indent_level -= indent_amount >>>> + def increase(self, amount: int = 4) -> int: >>>> + """Increase the indentation level by `amount`, default 4.""" >>>> + self._level += amount >>>> + return self._level >>>> + >>>> + def decrease(self, amount: int = 4) -> int: >>>> + """Decrease the indentation level by `amount`, default 4.""" >>>> + if self._level < amount: >>>> + raise ArithmeticError( >>>> + f"Can't remove {amount:d} spaces from {self!r}") >>>> + self._level -= amount >>>> + return self._level >>>> + >>>> + >>>> +indent = Indentation() >>> Personally, I would keep the push_indent(), pop_indent() API, and >>> introduce an indent() function, to follow the existing API style >>> of plain functions. >>> Something like: >>> indent_prefixes = [] >>> def push_indent(amount=4): >>> """Add `amount` spaces to indentation prefix""" >>> indent_prefixes.push(' '*amount) >>> def pop_indent(): >>> """Revert the most recent push_indent() call""" >>> indent_prefixes.pop() >>> def indent(): >>> """Return the current indentation prefix""" >>> return ''.join(indent_prefixes) >>> What you did is still an improvement, though, so: >>> Reviewed-by: Eduardo Habkost >>> >> >> Yeah, there's only one user right now, so ... I just kinda wanted to >> get rid of the global usage. Maybe if we make the code generator >> fancier we'll find out what form is best. > > You don't get rid of the global variable, you just change it from > integer to a class. A class can be handier when generating multiple > things interleaved, because you can have one class instance per thing. > The 'global' keyword, not 'global scoped'. The key thing was to remove re-binding of the global name, which is now true. We bind to this object once and then modify object state. The global keyword allows us to re-bind the variable at the global scope which is the pattern to avoid. Having globally scoped things you don't rebind is perfectly fine. > Note that we already have a class instance per thing we generate: > instances of subtypes of QAPIGen. The thought of moving the indentation > machinery into QAPIGen or or maybe QAPIGenCCode crossed my mind many > moons ago, but I had bigger fish to fry, and then I forgot :) > > John, I suggest you don't try to make this pretty just yet. Do what > needs to be done for the type hint job. We can make it pretty later. > Mmhmm. I'm fine with with we have here for now. We can try to make things pretty later. We have the rust support series to consider, too, so I am not going to put the cart before the horse. --js