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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]:46496 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kQYvs-0006TX-Ci for qemu-devel@archiver.kernel.org; Thu, 08 Oct 2020 12:38:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40350) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kQYv4-0005zH-50 for qemu-devel@nongnu.org; Thu, 08 Oct 2020 12:37:30 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:54006) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kQYv1-0001I1-3W for qemu-devel@nongnu.org; Thu, 08 Oct 2020 12:37:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602175046; 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=dxxONaYem8O7JVEiRaa/6Mh1KS4eQrfVxEls5syAK3A=; b=CjDpyayTrTIW93FsbdjTHapeHlytP4sSE1aU0+a+97TXukzBRZE4doZTghQokKyIqe77J5 OTB0A6ON1NkdRz9+qF5E2kXdkKOZYtki2oHy5ip7Gi8hfBo6bk3yuK92ROOuokcX4e+JC4 H7gFvMmAEW/XB80VcL6AxcrZ3Jh4LT8= 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-561-UVJgbQunPQCeXDp6sQcolg-1; Thu, 08 Oct 2020 12:37:24 -0400 X-MC-Unique: UVJgbQunPQCeXDp6sQcolg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 48D418070F0 for ; Thu, 8 Oct 2020 16:37:23 +0000 (UTC) Received: from [10.10.120.38] (ovpn-120-38.rdu2.redhat.com [10.10.120.38]) by smtp.corp.redhat.com (Postfix) with ESMTP id 99F241001281; Thu, 8 Oct 2020 16:37:22 +0000 (UTC) Subject: Re: [PATCH v5 03/36] qapi-gen: Separate arg-parsing from generation To: Markus Armbruster References: <20201005195158.2348217-1-jsnow@redhat.com> <20201005195158.2348217-4-jsnow@redhat.com> <877ds2jw6t.fsf@dusky.pond.sub.org> <007985f2-2872-1ab7-16aa-19414ba8cc78@redhat.com> <87d01t43de.fsf@dusky.pond.sub.org> From: John Snow Message-ID: <69a5950a-0b38-d819-641a-3ef4962974d8@redhat.com> Date: Thu, 8 Oct 2020 12:37:22 -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: <87d01t43de.fsf@dusky.pond.sub.org> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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 = 2020/10/08 02:56:27 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.214, RCVD_IN_DNSWL_NONE=-0.0001, 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: Cleber Rosa , qemu-devel@nongnu.org, Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/8/20 2:51 AM, Markus Armbruster wrote: > John Snow writes: > >> On 10/7/20 4:07 AM, Markus Armbruster wrote: >>> John Snow writes: >>> >>>> This is a minor re-work of the entrypoint script. It isolates a >>>> generate() method from the actual command-line mechanism. >>>> >>>> Signed-off-by: John Snow >>>> Reviewed-by: Eduardo Habkost >>>> Reviewed-by: Cleber Rosa >>>> Tested-by: Cleber Rosa >>>> --- >>>> scripts/qapi-gen.py | 85 +++++++++++++++++++++++++++++++++------------ >>>> 1 file changed, 62 insertions(+), 23 deletions(-) >>>> >>>> diff --git a/scripts/qapi-gen.py b/scripts/qapi-gen.py >>>> index 541e8c1f55d..117b396a595 100644 >>>> --- a/scripts/qapi-gen.py >>>> +++ b/scripts/qapi-gen.py >>>> @@ -1,30 +1,77 @@ >>>> #!/usr/bin/env python3 >>>> -# QAPI generator >>>> -# >>>> + >>>> # This work is licensed under the terms of the GNU GPL, version 2 or later. >>>> # See the COPYING file in the top-level directory. >>>> +""" >>>> +QAPI Generator >>>> + >>>> +This script is the main entry point for generating C code from the QAPI schema. >>>> +""" >>>> import argparse >>>> import re >>>> import sys >>>> from qapi.commands import gen_commands >>>> +from qapi.error import QAPIError >>>> from qapi.events import gen_events >>>> from qapi.introspect import gen_introspect >>>> -from qapi.schema import QAPIError, QAPISchema >>>> +from qapi.schema import QAPISchema >>>> from qapi.types import gen_types >>>> from qapi.visit import gen_visit >>>> >>>> -def main(argv): >>>> +DEFAULT_OUTPUT_DIR = '' >>>> +DEFAULT_PREFIX = '' >>>> + >>>> + >>>> +def generate(schema_file: str, >>>> + output_dir: str, >>>> + prefix: str, >>>> + unmask: bool = False, >>>> + builtins: bool = False) -> None: >>>> + """ >>>> + generate uses a given schema to produce C code in the target directory. >>>> + >>>> + :param schema_file: The primary QAPI schema file. >>>> + :param output_dir: The output directory to store generated code. >>>> + :param prefix: Optional C-code prefix for symbol names. >>>> + :param unmask: Expose non-ABI names through introspection? >>>> + :param builtins: Generate code for built-in types? >>>> + >>>> + :raise QAPIError: On failures. >>>> + """ >>>> + match = re.match(r'([A-Za-z_.-][A-Za-z0-9_.-]*)?', prefix) >>>> + if match.end() != len(prefix): >>>> + msg = "funny character '{:s}' in prefix '{:s}'".format( >>>> + prefix[match.end()], prefix) >>>> + raise QAPIError('', None, msg) >>>> + >>>> + schema = QAPISchema(schema_file) >>>> + gen_types(schema, output_dir, prefix, builtins) >>>> + gen_visit(schema, output_dir, prefix, builtins) >>>> + gen_commands(schema, output_dir, prefix) >>>> + gen_events(schema, output_dir, prefix) >>>> + gen_introspect(schema, output_dir, prefix, unmask) >>>> + >>>> + >>>> +def main() -> int: >>>> + """ >>>> + gapi-gen shell script entrypoint. >>> What's a "shell script entrypoint"? >>> Python docs talk about "when [...] run as a script": >>> https://docs.python.org/3/library/__main__.html >>> Similar: >>> https://docs.python.org/3/tutorial/modules.html#executing-modules-as-scripts >>> >> >> "entrypoint" is Python garble for a function that can be registered as >> a callable from the command line. >> >> So in a theoretical setup.py, you'd do something like: >> >> 'entry_points': { >> 'console_scripts': [ >> 'qapi-gen = qapi.main:main', >> ] >> } >> >> so when I say "shell script entrypoint", I am referring to a shell >> script (I mean: it has a shebang and can be executed by an interactive >> shell process) that calls the entrypoint. > > It can be executed by any process. See execve(2): > > pathname must be either a binary executable, or a script starting with > a line of the form: > > #!interpreter [optional-arg] > > For details of the latter case, see "Interpreter scripts" below. > > "Entry point" makes sense in Python context, "script entry point" also > makes sense (since every Python program is a script, script is > redundant, but not wrong). "Shell script entry point" is misleading. > >> Once (if) QAPI migrates to ./python/qemu/qapi, it will be possible to >> just generate that script. >> >> (i.e. doing `pip install qemu.qapi` will install a 'qapi-gen' CLI >> script for you. this is how packages like sphinx create the >> 'sphinx-build' script, etc.) >> >>>> + Expects arguments via sys.argv, see --help for details. >>>> + >>>> + :return: int, 0 on success, 1 on failure. >>>> + """ >>>> parser = argparse.ArgumentParser( >>>> description='Generate code from a QAPI schema') >>>> parser.add_argument('-b', '--builtins', action='store_true', >>>> help="generate code for built-in types") >>>> - parser.add_argument('-o', '--output-dir', action='store', default='', >>>> + parser.add_argument('-o', '--output-dir', action='store', >>>> + default=DEFAULT_OUTPUT_DIR, >>>> help="write output to directory OUTPUT_DIR") >>>> - parser.add_argument('-p', '--prefix', action='store', default='', >>>> + parser.add_argument('-p', '--prefix', action='store', >>>> + default=DEFAULT_PREFIX, >>>> help="prefix for symbols") >>>> parser.add_argument('-u', '--unmask-non-abi-names', action='store_true', >>>> dest='unmask', >>>> @@ -32,25 +79,17 @@ def main(argv): >>>> parser.add_argument('schema', action='store') >>>> args = parser.parse_args() >>>> - match = re.match(r'([A-Za-z_.-][A-Za-z0-9_.-]*)?', >>>> args.prefix) >>>> - if match.end() != len(args.prefix): >>>> - print("%s: 'funny character '%s' in argument of --prefix" >>>> - % (sys.argv[0], args.prefix[match.end()]), >>>> - file=sys.stderr) >>>> - sys.exit(1) >>>> - >>>> try: >>>> - schema = QAPISchema(args.schema) >>>> + generate(args.schema, >>>> + output_dir=args.output_dir, >>>> + prefix=args.prefix, >>>> + unmask=args.unmask, >>>> + builtins=args.builtins) >>>> except QAPIError as err: >>>> - print(err, file=sys.stderr) >>>> - exit(1) >>>> - >>>> - gen_types(schema, args.output_dir, args.prefix, args.builtins) >>>> - gen_visit(schema, args.output_dir, args.prefix, args.builtins) >>>> - gen_commands(schema, args.output_dir, args.prefix) >>>> - gen_events(schema, args.output_dir, args.prefix) >>>> - gen_introspect(schema, args.output_dir, args.prefix, args.unmask) >>>> + print(f"{sys.argv[0]}: {str(err)}", file=sys.stderr) >>>> + return 1 >>>> + return 0 >>>> >>>> if __name__ == '__main__': >>>> - main(sys.argv) >>>> + sys.exit(main()) >>> What does sys.exit() really buy us here? I'm asking because both >>> spots >>> in the Python docs I referenced above do without. >>> >> >> It just pushes the sys.exit out of the main function so it can be >> invoked by other machinery. (And takes the return code from main and >> turns it into the return code for the process.) >> >> I don't think it winds up mattering for simple "console_script" entry >> points, but you don't want the called function to exit and deny the >> caller the chance to do their own tidying post-call. >> >> You've already offered a "YAGNI", but it's just the convention I tend >> to stick to for how to structure entry points. > > I'm not questioning the conventional if __name__ == '__main__' menuett. > I wonder why *we* need sys.exit() where the examples in the Python docs > don't. > I assume they don't care about setting that return code manually. By default it's going to be 0 on normal exit, and non-zero if it raises or aborts. We catch the error to pretty-print it to console instead, and want to avoid the stack trace so we return a status code instead. I assume that's the only difference, really. --js