[Python-Dev] Inplace operations for PyLong objects (original) (raw)

Joe Jevnik jjevnik at quantopian.com
Fri Sep 1 16:35:41 EDT 2017

Is it true that checking for refcount == 1 is enough? What if a user wrote:

args = (compute_integer(), 5)

give away args to someone

int.iadd(*args)

here args[0] still has refcount=1 because only args owns this integer.

On Fri, Sep 1, 2017 at 4:19 PM, Jelle Zijlstra <jelle.zijlstra at gmail.com> wrote:

2017-09-01 13:05 GMT-07:00 Chris Barker <chris.barker at noaa.gov>: On Thu, Aug 31, 2017 at 5:12 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:

I'm skeptical there are some programs out there that are limited by the speed of PyLong inplace additions.

indeed, but that could be said about any number of operations. My question is -- how can the interpreter know if it can alter what is supposed to be an immutable in-place? If it's used only internally to a function, the it would be safe, but how to know that? I believe Catalin's implementation checks if the object's refcount is 1. If that is the case, it is safe to mutate it. -CHB

-- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception Chris.Barker at noaa.gov

Python-Dev mailing list Python-Dev at python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/jelle. zijlstra%40gmail.com

Python-Dev mailing list Python-Dev at python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/ joe%40quantopian.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20170901/ccb27cad/attachment.html>

More information about the Python-Dev mailing list