PS: On 2013-09-03, Simon King <simon.k...@uni-jena.de> wrote: > Shouldn't there always be a coercion from the base ring into a > unital algebra? It seems to me that the underlying problem is that > matrix spaces do not properly use the new coercion model (in particular, > they define their own __call__, how nasty!).
Looking at what I wrote later in my previous post, I think this is *not* the problem. Since the previous post was so long, here is a summary: - For efficience reasons, we do not want full category initialisation during __init__ (please don't change this, unless you want to mess with the number theorists...) => __init_extra__ of Algebras.ParentMethods is not called => one needs to establish an action from the base ring "manually" - The category *is* initialised for CategoryObject, but just not for Parent. It would be a good idea to check whether IntegralDomains() could be used in the category, since this is needed for FractionField to be defined. - The usual framework for actions of a base ring on a module relies on cpdef methods _rmul_ and _lmul_. Problem: These expect their input of a particular type, that is often *not* used in sage.combinat. - I recommend to *try* (no guarantee it will work) to create a new type of action "A" (inherit from sage.categories.action.Action). You need to implement its _call_ and _repr_name_, and I think that's all what is to do (but perhaps you'll find other examples of Action in Sage, so, try to learn from existing code). Typically, the _call_ method of the action A._call_(a,b) will rely on methods of a and b (in our application, "a" is element of the base ring and "b" is a matrix). And then, let MatrixSpace._get_action_ return A. Hope the short version of my post was helpful :) Best regards, Simon -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-combinat-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-combinat-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-combinat-devel. For more options, visit https://groups.google.com/groups/opt_out.
