On Thu, Sep 19, 2013 at 9:48 AM, Peter Bruin <pjbr...@gmail.com> wrote: > I don't think I said that I wanted more static inheritance. > > >> Basically, you want >> >> class IntegralDomainElement(Element): >> ... >> >> class IntegralDomain(Parent): >> ... >> >> class EuclideanDomainElement(IntegralDomainElement): >> def xgcd(self, other): >> ... >> >> class EuclideanDomain(IntegralDomain): >> Element = EuclideanDomainElement >> >> class EuclideanDomains(IntegralDomains): >> ParentMethods = EuclideanDomain >> >> instead of >> >> class EuclideanDomainElement: >> def xgcd(self, other): >> ... >> >> class EuclideanDomain: >> ... >> >> class EuclideanDomains(IntegralDomains): >> ElementMethods = EuclideanDomainElement >> ParentMethods = EuclideanDomain > > > No, I want > > class IntegralDomainElement(Element): > ... > > class IntegralDomain(Parent): > Element = IntegralDomainElement >> >> class EuclideanDomainElement(Element): >> def xgcd(self, other): >> ... >> class EuclideanDomain(Parent): >> Element = EuclideanDomainElement > > class IntegralDomains(Category_singleton): > ParentMethods = IntegralDomain > > class EuclideanDomains(Category_singleton): > ParentMethods = EuclideanDomain > > def super_categories(self): > return [IntegralDomains()]
So you don't actually want the long inheritance as seen in https://github.com/sagemath/sage/blob/8118b2b39e3a129a5a6186fdc9917940f92b87a6/src/sage/structure/element.pyx#L2773 > I would expect the category framework to figure out that if R is an object > in EuclideanDomains, then R.element_class should dynamically inherit from > both EuclideanDomainElement and IntegralDomainElement. It already does. R need not descend from EuclideanDomain, it simply declares its category as EuclideanDomains. The difference between your proposal and what currently exists are (1) The Element[Methods] class is attached to the category's ParentMethods, rather than the category itself and (2) The Element and Object method classes are required to inherit from Element and Parent directly. I don't see what value this adds, as the concrete R.element_class values will already have this property. > Less importantly, I would also prefer ParentMethods to be called Object, > ObjectClass or something similar, both because objects needn't be parents > and because the class in question could have other attributes that are not > methods. Yeah. Unfortunately, we have object and SageObject that mean entirely different things. There is also CategoryObject which is a superclass of Parent (=Object in the category of Sets). Element doesn't actually makes sense on CategoryObject. - Robert -- 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/groups/opt_out.
