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bh=nkGifd19yOmg59pMMcDC5W4L+0GufPAEDNr8VMwdTTI=; b=B/Zy5WOSUXr+VS++iP0pZZYQO69S5ve+qa7bE9NMi+p9R3H4WknvFtIfZx68CzPfXd6xiw T21EluIF8SoyKXhiWQgYrW20dUF0SzI5eLf1tdpNa/2vDYlJSkuMFUi3beppsCQcEAXeAK 9hyw0TH4Jq4MMwFr4nD9WRb8zvP6h8w= 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-405-tDYeFqVeOk2OEu6y1UC6jg-1; Fri, 25 Sep 2020 09:25:04 -0400 X-MC-Unique: tDYeFqVeOk2OEu6y1UC6jg-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 B8AE91008559; Fri, 25 Sep 2020 13:25:02 +0000 (UTC) Received: from redhat.com (ovpn-114-208.ams2.redhat.com [10.36.114.208]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C52115D9F3; Fri, 25 Sep 2020 13:25:00 +0000 (UTC) Date: Fri, 25 Sep 2020 14:24:58 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Subject: Re: [PATCH v2 28/38] qapi/gen.py: update write() to be more idiomatic Message-ID: <20200925132458.GJ2178035@redhat.com> References: <20200922210101.4081073-1-jsnow@redhat.com> <20200922210101.4081073-29-jsnow@redhat.com> <20200923152624.GO3312949@habkost.net> <20200924155959.GC191229@localhost.localdomain> <87r1qqro8i.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87r1qqro8i.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=berrange@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: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 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, 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Peter Maydell , Eduardo Habkost , Alex =?utf-8?Q?Benn=C3=A9e?= , Michael Roth , qemu-devel@nongnu.org, Cleber Rosa , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Sep 25, 2020 at 03:15:57PM +0200, Markus Armbruster wrote: > Cleber Rosa writes: > > > On Wed, Sep 23, 2020 at 02:37:27PM -0400, John Snow wrote: > >> On 9/23/20 11:26 AM, Eduardo Habkost wrote: > >> > On Tue, Sep 22, 2020 at 05:00:51PM -0400, John Snow wrote: > >> > > Make the file handling here just a tiny bit more idiomatic. > >> > > (I realize this is heavily subjective.) > >> > > > >> > > Use exist_ok=True for os.makedirs and remove the exception, > >> > > use fdopen() to wrap the file descriptor in a File-like object, > >> > > and use a context manager for managing the file pointer. > >> > > > >> > > Signed-off-by: John Snow > >> > > >> > Reviewed-by: Eduardo Habkost > >> > > >> > I really miss a comment below explaining why we use > >> > open(os.open(pathname, ...), ...) instead of open(pathname, ...). > > This code: > > fd = os.open(pathname, os.O_RDWR | os.O_CREAT, 0o666) > f = open(fd, 'r+', encoding='utf-8') > > >> Not known to me. It was introduced in 907b846653 as part of an effort to > >> reduce rebuild times. Maybe this avoids a modification time change if the > >> file already exists? > >> > >> Markus? > > > > AFACIT the change on 907b846653 is effective because of the "is new > > text different from old text?" conditional. I can not see how the > > separate/duplicate open/fdopen would contribute to that. > > > > But, let's hear from Markus. > > This was my best attempt to open the file read/write, creating it if it > doesn't exist. > > Plain > > f = open(pathname, "r+", encoding='utf-8') > > fails instead of creates, and > > f = open(pathname, "w+", encoding='utf-8') > > truncates. > > If you know a better way, tell me! IIUC, you need "a+" as the mode, rather than "w+" Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|