On Mar 12, 2009, at 2:24 PM, Jason Grout wrote: > Robert Bradshaw wrote: >> I'm glad the coercion model is starting to get discussed, >> implemented, and used by other people. Before it gets to popular, I >> would like to propose an api change. >> >> Currently, if A has an action on B (where B is not an A-module) one >> implements either a._l_action_ or b._r_action_. This is because >> sometimes it makes sense to put the method on the actor (e.g. Galois >> groups acting on field elements) and sometimes on the acted on (e.g. >> matrices acting on quadratic forms). However, the _x_action_ is hard >> to remember and doesn't always correspond to right/left actions. This >> may be why they're hardly used up to this point. >> >> The proposal is to make the methods a._act_on_(b, self_on_left) and >> b._acted_upon_(a, self_on_left). In other words, a*b would try >> "a._act_on_(b, True)" and "b._acted_upon_(a, False)". This wouldn't >> be a fundamental change on how things work, just mainly a naming >> change, but I though it would be a good idea to run it by here. > > > So if I'm being confusing (or wrong!) here, tell me. Right now, a > vector*matrix is thought of as a matrix acting on the vector, right? > (This might be where I'm confused because I'm too used to > matrix*vector > constructs.)
Yes. > But then the above would force that this would be > contained in the vector._act_on_ or the matrix._acted_upon_ methods, > right? This seems backwards... It would be implemented in the matrix._act_on_ or vector._acted_upon_ methods. (Though in this case there is an actual "Action" object defined in http://hg.sagemath.org/sage-main/file/b0aa7ef45b3c/sage/ matrix/action.pyx that is used, and MatrixSpace implements _get_action_). - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
