Would it be better to have a UnitaryRing subclass? It'd be a bit more work but would be a bit more natural since not all rings have a unit.
On 5/24/07, Nick Alexander <[EMAIL PROTECTED]> wrote: > > David Harvey <[EMAIL PROTECTED]> writes: > > > On May 24, 2007, at 1:53 PM, Michel wrote: > > > >> > >> My apologies if I have misunderstood things. I am doing some pyrex > >> programming and I see there are many pitfalls (like writing !=None :-) > >> > >> I encountered the following problem: > >> If I understand correctly then rings have a _zero_element attribute > >> but not a _unit_element > >> attribute. Since you often want to initialize something to 1, not > >> having a unit element is inconvenient. > >> > >> Of course you can create the unit element as R(1) but this seems to be > >> expensive and has > >> unpredicable performance (it depends on the implementation of the > >> __call__ method of R). > >> Furthermore you want there to be a unique unit element for efficiency > >> of testing. > >> > >> So unless I have misunderstood things (which is quite likely) I would > >> propose to give > >> rings a _unit_element attribute which is initialized in the > >> constructor. > > > > Strong +1 for this. I can't believe we don't already have it :-) > > > > Not sure I would want it called _unit_ though, makes me think rather > > of invertible elements. How about _one_, or _unity_? > > +1 to _one_. > > Nick > > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
