[Python-Dev] Usage of += on strings in loops in stdlib

[Antoine Pitrou]

On Tue, 12 Feb 2013 13:32:50 -0800
"fwierzbicki at gmail.com" <fwierzbicki at gmail.com> wrote:
> On Tue, Feb 12, 2013 at 1:03 PM, Maciej Fijalkowski <fijall at gmail.com> wrote:
> > Hi
> >
> > We recently encountered a performance issue in stdlib for pypy. It
> > turned out that someone commited a performance "fix" that uses += for
> > strings instead of "".join() that was there before.
> >
> > Now this hurts pypy (we can mitigate it to some degree though) and
> > possible Jython and IronPython too.
> Just to confirm Jython does not have optimizations for += String and
> will do much better with the idiomatic "".join().

For the record, io.StringIO should be quite fast in 3.3.
(except for the method call overhead that Guido is complaining
about :-))

Regards

Antoine.