Hey, > I wonder: Is it really the case that one single parent P, which is an > instance of a parent class P_class, shall simultaneously have elements > of type MyElementA and MyElementB? Or is it rather the case that you > have one single parent class P_class, and then have two instances P_A > and P_B of P_class, where P_A's elements should be instances of > MyElementA and P_B's elements of MyElementB? >
Once Homsets are proper Parents, I think we will run into such situations where we want two separate classes for different types of morphisms because they behave fundamentally different. I came across this with crystals (http://trac.sagemath.org/ticket/15463), where there are usual morphisms and a "twisted" version, and I couldn't pass the info though Hom either. Another (and broader) example would be graded modules, where we have morphism which preserve grading and those with a grading shift. I wouldn't want to put morphisms with a grading shift just as a module morphism since the grading is essentially preserved, but I would want those morphisms with a grading shift to be in a different class fundamentally. Granted one could consider morphisms which preserve the grading as having a shift of 0, but then many methods like _repr_type would have a bunch of `if` statements that would suggest separate classes IMO. Best, Travis -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
