PrimaryFeather/Sparrow-Framework — pull request #1060 by tconkling (2012-03-27 17:58:34+00:00)
Title: Provide hash functions for SPPoint, SPRectangle, and SPMatrix.

Since equality is not transitive in these float-based classes, we can't
compute a good hash function - but a poor hash is better than the default,
which breaks the "if isEqual(a,b) then hash(a) == hash(b)" contract.

(Without hash functions, if you (inadvisably) try to use any of these classes as keys in containers, the behavior is undefined.)