[Python-Dev] optimization required: .format() is much slower than % (original) (raw)
Antoine Pitrou solipsis at pitrou.net
Sun Jun 1 00:45:24 CEST 2008
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Simon Cross <hodgestar gmail.com> writes:
My tests show that the old-style % formatting is much faster when the final string is 20 characters or less:
$ ./python -m timeit "'....|....|....|...%s' % '12'" 10000000 loops, best of 3: 0.0764 usec per loop
You are the victim of a constant-folding optimization:
$ ./python -m timeit "'....|....|....|...%s' % '12'" 10000000 loops, best of 3: 0.0926 usec per loop $ ./python -m timeit -s "s='12'" "'....|....|....|...%s' % s" 1000000 loops, best of 3: 0.525 usec per loop
def f(): return '....|....|....|...%s' % '12' ... dis.dis(f) 1 0 LOAD_CONST 3 ('....|....|....|...12') 3 RETURN_VALUE
cheers
Antoine.
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