[Python-Dev] Revising RE docs

Fri Sep 2 12:40:35 CEST 2005

On Thursday 2005年09月01日 18:09, Guido van Rossum wrote:
> They *are* cached and there is no cost to using the functions instead
> of the methods unless you have so many regexps in your program that
> the cache is cleared (the limit is 100).

Sure there is; the cost of looking them up in the cache.
 >>> import re,timeit
 >>> timeit.re=re
 >>> timeit.Timer("""re.search(r"(\d*).*(\d*)", "abc123def456")""").timeit(1000000)
 7.6042091846466064
 >>> timeit.r = re.compile(r"(\d*).*(\d*)")
 >>> timeit.Timer("""r.search("abc123def456")""").timeit(1000000)
 2.6358869075775146
 >>> timeit.Timer().timeit(1000000)
 0.091850996017456055
So in this (highly artificial toy) application it's about 7.5/2.5 = 3 times
faster to use the methods instead of the functions.
-- 
g