On Mon, Aug 24, 2009 at 10:43 PM, Robert Bradshaw<rober...@math.washington.edu> wrote: > > On Aug 23, 2009, at 12:42 PM, William Stein wrote: > >> On Sun, Aug 23, 2009 at 12:27 PM, Sebastian Pancratz >> <s...@pancratz.org> wrote: >> >> I think as a first step I'll only implement the additional argument >> for the two methods "is_field" and "is_integral_domain". > > +1 to this idea. > >> For the other suggestion, namely to allow the user to assert that a >> ring is in fact a field, would the following be the "right" way to >> implement this? 1. Add a new attribute to the ring class, say >> IS_FIELD, initialised to None, 2. Implement "assert_field(check)" to >> set IS_FIELD = check, 3. Change "is_field" such that (ignoring the >> issue about raising an exception or returning False) if IS_FIELD is >> None it should behave as now and otherwise it should return the value >> of IS_FIELD. >> >> Don't make it upper case. Make the attribute _is_field. Otherwise >> the above sounds great to me. > > I'm not sure about this--it means everyone implementing an is_field > method will have to know about this "trick" and the number of > properties to know about grows as the number of is_* methods.
You have a really good point. > What I'd rather see is something like > > sage: R = Zmod(6) > sage: K = categories.Fields(R, check=False) # any ring R > sage: K > Ring of integers modulo 6 as a field. > sage: K.is_field() > True > > where all other methods are inherited via dynamically. That would be pretty cool. I'm not sure if I like sage: K = categories.Fields(R, check=False) since it could be hard for me to remember. That said, it does fit the "Sage/Magma" design philosophy pretty nicely, and is a natural way to use coercions and categories. Cool idea. William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
