.format vs. %

Tue Jan 3 09:17:15 EST 2012

Neil Cerutti <neilc at norwich.edu> wrote:
> > 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))
> ...

Did you profile this? I did, and it still adds 22% to the runtime.
Stefan Krah