On Mar 11, 2009, at 1:21 PM, Florent Hivert wrote: > >> How many places is this used? In my (fairly fresh) Sage session, >> there are only 9 actions in the action cache (on matrices, number >> fields, and polynomials). I'd be willing to write the _get_action_ >> methods for these cases, if it would help kill off some of the excess >> error catching in coercion (I'm really not very fond of the idea "try >> it to see if it will work", anyway). > > +1 to remove the try if it's work.
Matrices are already implemented via the _get_action_ path. For polynomials and number fields, I think it's actually cleaner to just provide _rmul_ and _lmul_ than create an actions (especially in terms of subclassing). > The very purpose of the category framework it to declare in a > mathematical > way, this that have a matematical meaning. In the case of a right > action of A > on B, on declare that B is a A-RightModule. It is much more > informative by all > respect than testing if a random element of A accept to be > multiplied by a > random element of B. _rmul_ and _lmul_ are only tried if B is an A-module. (We don't (yet) have the distinction between right and left modules, this is part of where the "try it out" comes into play). However, not all actions are module actions, e.g. a permutation acting on an ordered list, or a matrix acting on a quadratic form (to take two examples that I've been thinking about lately). - 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 -~----------~----~----~----~------~----~------~--~---
