Hi Andrey! (oups, I see that I misspelled your name recently; sorry!)
On Fri, Mar 18, 2011 at 11:42:27AM -0700, Andrey Novoseltsev wrote: > We have a heated debate on http://trac.sagemath.org/sage_trac/ticket/10140 > regarding the following issue. > > When a user writes > > Cone(rays=[(1,0), (0,1)]) > > and the internal framework that eliminates unnecessary generators > comes up with a cone generated by (0,1) and (1,0) (i.e. same rays but > in reversed order), should the order given by the user restored by > default, or should we have > > sage: C = Cone(rays=[(1,0), (0,1)]) > sage: C.rays() > [(0,1), (1,0)] > > Obviously, any case is mathematically valid. > > I argue that if a user gives rays in certain order, then (s)he may > want them in that particular order. (Restoring the order may be a slow > down, but there can be an optional parameter to turn it off.) > > Volker argues that we should not make cones decorated unless we are > explicitly asked to. (Those who care about the order, should use some > other class/function like OrderedCone.) > > More details/issues are available on the ticket, but since many of > them are a matter of taste and personal preferences, it would be nice > to hear what do multiple people think of it, not just two of us ;-) Just two cents from an outsider (I'll certainly will have a need for Cone's at some point, but don't have practical experience). When there is no clear cut answer for a design decision, I tend, whenever possible, to just postpone it; more often than not, the answer will become clear by itself after accumulating practical experience. In that case, there could be an option like: Cone(rays=[(1,0),(0,1)], keep_order = True) and the documentation could explicitly specify that the default value is currently *undefined*, and will be chosen later on. I guess for the moment I would unofficially set it to False, since that's the cheapest while True is somehow "adding a feature"; so that's less likely to break code in case of change later on. Cheers, Nicolas -- Nicolas M. Thiéry "Isil" <nthi...@users.sf.net> http://Nicolas.Thiery.name/ -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To post to this group, send email to sage-combinat-devel@googlegroups.com. To unsubscribe from this group, send email to sage-combinat-devel+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sage-combinat-devel?hl=en.
