[Python-ideas] Briefer string format

[Tim Peters]

[Alexander Belopolsky]
> One thing I know for a fact is that the use of % formatting instead of
> .format makes a significant difference in my applications.  This is not
> surprising given these timings:
>
> $ python3 -mtimeit "'%d' % 2"
> 100000000 loops, best of 3: 0.00966 usec per loop
> $ python3 -mtimeit "'{}'.format(2)"
> 1000000 loops, best of 3: 0.216 usec per loop

Well, be sure to check what you're actually timing.  Here under Python 3.4.3:

>>> from dis import dis
>>> def f():
           return "%d" % 2
>>> dis(f)
  2           0 LOAD_CONST               3 ('2')
              3 RETURN_VALUE

That is, the peephole optimizer got rid of "%d" % 2 entirely,
replacing it with the string constant "2".  So, in all, it's more
surprising that it takes so long to load a constant ;-)