Hi! I think I have solved the main problem!!
I am now able to do: sage: class Foo: ....: __metaclass__ = FastHash ....: def __hash__(self): ....: print "computing hash" ....: return id(self) ....: sage: f = Foo() When calling the hash for the first time, it is computed: sage: hash(f) computing hash 91791312 The second time, it is taken from cache: sage: hash(f) 91791312 It is quite fast: sage: %timeit hash(f) 625 loops, best of 3: 557 ns per loop Compare that timing with "the same" class without metaclass: sage: class Bar: ....: def __hash__(self): ....: return id(self) ....: sage: b = Bar() sage: hash(b) 91765648 sage: %timeit hash(b) 625 loops, best of 3: 1.06 µs per loop Another example. I create a fast-hash version of a univariate polynomial class: sage: MyPolyRing = FastHash(QQ['x'].__class__) sage: P = MyPolyRing(QQ,'y') sage: P Univariate Polynomial Ring in y over Rational Field The hash is the same as the "slow" hash: sage: Q = QQ['y'] sage: hash(P) 7267929297229424747 sage: P is Q False sage: hash(Q) == hash(P) True It is faster: sage: %timeit hash(P) 625 loops, best of 3: 560 ns per loop sage: %timeit hash(Q) 625 loops, best of 3: 3.13 µs per loop And even better: The speed-up is available *after* initialisation as well! sage: Q.__class__ = FastHash(Q.__class__) sage: %timeit hash(Q) 625 loops, best of 3: 562 ns per loop Conclusion: What I did might be a convenient way to take an existing Python class and speed-up its __hash__ using Cython. Todo: Pickling. Best regards, Simon -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
