On 2017-12-19, Jeroen Demeyer <jdeme...@cage.ugent.be> wrote: >> My >> understanding is that B._coerce_map_from_(A) returning "True" is a >> mathematical statement > > Right, but this isn't how Sage works. There is no way to ask for > mathematical properties of a Parent. There are categories, but those are > much too weak: you can know that a parent is a field, but not whether > all elements are real numbers for example.
The parent is supposed to know, and thus to return "True" (or a map) for all incarnations of the real field. >> On the other hand, it *is* possible to return a map. So, of cource you >> could check in B._coerce_map_from_(A) whether a named conversion is >> available, and return it. > > Yes, that was my idea. But it needs some changes to the coercion > framework, which is why I created https://trac.sagemath.org/ticket/24381 Why "changes in the framework"? Isn't it possible to exploit what the current framework has to offer? Cheers, Simon -- 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 https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
