On Fri, Jul 8, 2011 at 11:30 PM, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > Billy Mays wrote: > >> If it means anything, I think concatenation is faster. > > You are measuring the speed of an implementation-specific optimization. > You'll likely get *very* different results with Jython or IronPython, or > old versions of CPython, or even if you use instance attributes instead of > local variables. > > It also doesn't generalise: only appends are optimized, not prepends.
Indeed: $ python -m timeit -s "v = 'x' * 10; out = ''" "out = out + v" 1000000 loops, best of 3: 6.59 usec per loop $ python -m timeit -s "v = 'x' * 10; out = ''" "out = v + out" 100000 loops, best of 3: 268 usec per loop Good to know. I had no idea such an optimization existed. Cheers, Ian -- http://mail.python.org/mailman/listinfo/python-list
