[Python-Dev] PEP 552: deterministic pycs (original) (raw)

Brett Cannon brett at python.org
Wed Sep 20 18:37:51 EDT 2017

On Fri, 8 Sep 2017 at 10:53 Benjamin Peterson <benjamin at python.org> wrote:

Thank you all for the feedback. I've now updated the PEP to specify a 4-word pyc header with a bit field in every case.

On Fri, Sep 8, 2017, at 09:43, Nick Coghlan wrote: > On 8 September 2017 at 07:55, Antoine Pitrou <solipsis at pitrou.net> wrote: > > On Fri, 8 Sep 2017 07:49:46 -0700 > > Nick Coghlan <ncoghlan at gmail.com> wrote: > >> > I'd rather a single magic number and a separate bitfield that tells > >> > what the header encodes exactly. We don't have to fight for a tiny > >> > size reduction of pyc files. > >> > >> One of Benjamin's goals was for the existing timestamp-based pyc > >> format to remain completely unchanged, so we need some kind of marker > >> in the magic number to indicate whether the file is using the new > >> format or nor. > > > > I don't think that's a useful goal, as long as we bump the magic number. > > Yeah, we (me, Benjamin, Greg) discussed that here, and we agree - > there isn't actually any benefit to keeping the timestamp based pyc's > using the same layout, since the magic number is already going to > change anyway. > > Given that, I think your suggested 16 byte header layout would be a > good one: 4 byte magic number, 4 bytes reserved for format flags, 8 > bytes with an interpretation that depends on the format flags. >

+1 from me! -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20170920/a285afb9/attachment.html>

More information about the Python-Dev mailing list