Hi Simon, Thank you for the explanation.
However, during the category initialisation, self is used as key in > some cache. Hence, it is needed that its hash value is available. By > default in sage.rings.ring.Ring, hash(self) is the self as > hash(repr(self)) > (which I don't like, by the way). > I am not against using the string representation to compute the hash, as the last resort. > There are two possible solutions: Either do > def __init__(self, i): > self._ideal = i > CommutativeAlgebra.__init__(self, i.base_ring()) > or define a __hash__ method that does not rely on the string > representation. > > The question is whether a meaningful hash is available before knowing > self._ideal. Hence, I recommend the first solution. > The first solution looks ugly. I think the problem lies in that the hash is calculated when the object is not fully constructed. The hash value should be calculated as the last part of the initialization process, as the hash should be dependent on the data that defines the object. As the "..Algebra.__init__" is expected to be placed at the beginning of the initialization code, I think there should be a separate method say "..Algebra._set_hash_" that is executed manually or automatically at the end of the initialization process. -- 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
