On Tue, May 5, 2015 at 2:10 PM, Eric Gourgoulhon <egourgoul...@gmail.com> wrote: > Hi, > > Le mardi 5 mai 2015 12:44:08 UTC+2, vdelecroix a écrit : >> >> >> IMHO, they do not belong either to parents. A set has generators? >> >> sage: Partitions(5).gens_dict() >> Traceback (most recent call last): >> ... >> AttributeError: 'StandardPermutations_n_with_category' object >> has no attribute 'gens'AttributeError: 'Partitions_n_with_category' >> > > In the same vein, shouldn't base_ring be removed from Parent as well ? > > sage: Set([1,2,3]).base_ring() > > The return value is None, which is arguably correct, for a generic set has > no base ring, but it might be surprising when using tab completion to > discover functionalities to see that a base_ring() method exists for such > objects.
As Parents have Elements, this is also the root of operations that deal with coercion (arithmetic between elements of unequal Parents). Some functions like base_ring are used for coercion, though arguments could be made that it could be moved elsewhere and called dynamically iff it exists. -- 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.
