On Sat, Mar 20, 2010 at 10:05 AM, Mark Dickinson <dicki...@gmail.com> wrote: > On Sat, Mar 20, 2010 at 3:17 PM, Case Vanhorsen <cas...@gmail.com> wrote: >> On Sat, Mar 20, 2010 at 4:06 AM, Mark Dickinson <dicki...@gmail.com> wrote: >>> What external modules are there that rely on existing hash behaviour? >> >> I'm only aware of gmpy and SAGE. >> >>> And exactly what behaviour do they rely on? >> >> Instead of calculating hash(long(mpz)), they calculate hash(mpz) >> directly. It avoids creation of a temporary object that could be quite >> large and is faster than the two-step process. I would need to modify >> the code so that it continues to produce the same result. > > Does gmpy only do this for Python 2.6? Or does it use different > algorithms for 2.4/2.5 and 2.6? As far as I can tell, there was no > reasonable way to compute long_hash directly at all before the > algorithm was changed for 2.6, unless you imitate exactly what Python > was doing (break up into 15-bit pieces, and do all the rotation and > addition exactly the same way), in which case you might as well be > calling long_hash directly. > > Mark >
It does the later: it converts from GMP's internal format to CPython's long format and calculates the hash along the way. I may (should :) ) revert back to converting to long and then calling long_hash. The majority of the speed increase came from the conversion improvements, not the hash calculation. I am in favor of any change that makes 2.7 and 3.2 behave the same. casevh _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
