Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!news.musoftware.de!wum.musoftware.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
From: Neil Cerutti <neilc@norwich.edu>
Newsgroups: comp.lang.python
Subject: Re: .format vs. %
Date: 3 Jan 2012 13:58:21 GMT
Organization: Norwich University
Lines: 37
Message-ID: <9mgfrtFt0U5@mid.individual.net>
References: <5642862.375.1325355574622.JavaMail.geo-discussion-forums@vbbhx10> <4EFF559E.1050408@gmail.com> <mailman.4321.1325544682.27778.python-list@python.org> <fd8933b8-0cca-4127-8f9b-38b056ee075a@h12g2000yqg.googlegroups.com> <4f027b79$0$29880$c3e8da3$5496439d@news.astraweb.com> <CALwzidnvLsamJ=TchqjhZCrXHnP0LyOvg+gSCo+zJ2Edy0W=7w@mail.gmail.com> <4F02DE94.8000506@gmail.com> <mailman.4345.1325591422.27778.python-list@python.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Trace: individual.net 26PzzwcrJrU3eb7Am0wkpw68NpVH7Uyd6cT4lXxzjCXME380Wr
Cancel-Lock: sha1:rRQoWaoeulB5EPwO69WRqweA5Ec=
User-Agent: slrn/0.9.9p1/mm/ao (Win32)
Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:18406

On 2012-01-03, Stefan Krah <stefan-usenet@bytereef.org> wrote:
> Andrew Berg <bahamutzero8825@gmail.com> wrote:
>> To add my opinion on it, I find format() much more readable and easier
>> to understand (with the exception of the {} {} {} {} syntax), and would
>> love to see %-style formatting phased out.
>
> For me the %-style is much more readable. Also, it is significantly
> faster:
>
> $ ./python -m timeit -n 1000000 '"%s" % 7.928137192'
> 1000000 loops, best of 3: 0.0164 usec per loop
> $ ./python -m timeit -n 1000000 '"{}".format(7.928137192)'
> 1000000 loops, best of 3: 1.01 usec per loop
>
> In the real-world telco benchmark for _decimal, replacing the
> single line
>
>     outfil.write("%s\n" % t)
>
> with
>
>     outfil.write("{}\n".format(t))
>
> adds 23% to the runtime. I think %-style formatting should not
> be deprecated at all.
   
When it becomes necessary, it's possible to optimize it by
hoisting out the name lookups.
   ...
   outfil_write = outfil.write
   append_newline = "{}\n".format
   ...
       outfil_write(append_newline(t))
       ...

-- 
Neil Cerutti