On Mar 12, 2009, at 8:47 PM, Nicolas M. Thiery wrote: > Dear Robert, > > Hmmm. Quite an interesting discussion. Could anyone try to make some > sort of synthesis of the different opinions expressed in this thread? > > On Thu, Mar 12, 2009 at 12:18:45PM -0700, Robert Bradshaw wrote: >> As mentioned, everything can be seen as a Z-module. This would mean >> that every time I implement _mul_ I would have to handle this case. >> It's much simpler to let _mul_ only worry about the ring (or group, >> or field...) multiplication. One can define _rmul_, _lmul_, ... for >> actions. > > +10 > > Just 2 cents: > > - I would reserve _lmul_, _rmul_ ... for actions which can be > considered as some sort of multiplication by scalars,
It is. The semantics for _rmul_ and _lmul_ are that the other element is guaranteed to be a scalar (i.e. a member of your basering). > and using another name like the one you suggested for other actions > > - I see 10*bla as (potentially) involving two independent things: > coercion and multiple dispatch Yep, though in my mind they're a bit more intertwined (e.g. for a \in Z, b \in QQ[x], one can do a*b by doing a coercion then an action, b._lmul_(QQ(a)). > For whatever it's worth, I had started writing a draft of paper on the > coercion (= implicit conversion) and multiple dispatch mechanism I had > implemented in MuPAD: > > http://mupad-combinat.svn.sourceforge.net/viewvc/mupad-combinat/ > trunk/MuPAD-Combinat/Papers/2007-12-13-Overloading.tex?view=markup > > Strangely enough, I lost part of my motivation for working on this > shortly after :-) I'll take a look. I've been intending to write this up as a paper too, but haven't found the time yet. - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send 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 -~----------~----~----~----~------~----~------~--~---
