On Sat, Mar 20, 2010 at 3:17 PM, Case Vanhorsen <casevh@gmail.com> wrote:
On Sat, Mar 20, 2010 at 4:06 AM, Mark Dickinson <dickinsm@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