Affine transforms - matrix algebra

[Richard Bair]

>>> Why don't we make hashcode a property?  ;)
>> 
>> In fact, it is! hashcode follows precisely the pattern for immutable
>> properties -- it is just a getter.
> 
> hashcode isn't immutable.  It is immutable only for objects that are themselves immutable (with a correctly written override) or for the default implementation.

While that is true, implementing hash code for mutable objects is fraught with peril (usages in hashMaps and such will be all messed up because the same object that was a key is now at a different hash location, etc).

Richard