On Feb 26, 2009, at 1:45 AM, Nicolas M. Thiery wrote: > Hi Sébastien! > >> Couldn't we define something like : >> >> def _len_(self): >> return ... >> >> that behave like we want as it is done for _str_ and _repr_ ? > > That could be an option. But: > > - It can be confusing for the user to have two functions with almost > the same name (__len__ / _len_) and subtle semantic difference. > (for the record, I also find _str_/__str__ confusing).
I agree--we mostly use this convention when some automated preprocessing/wrapping needs to be done, e.g. coercion. I think cardinality is the best name. > - We really want the function to appear in the automatic completion. > (or alternatively that could be called via a standard function like > len(...) had we been lucky enough to be able to use len). > > - len conveys more a computer science meaning rather than a > mathematical meaning. I could see __len__ calling cardinality, but raising an overflow error on infinite (or > maxint) results. BTW, NonNegative- and PostiveIntegers were implemented by David Roe as part of the Coercion branch, but never ended up getting merged over (partially due to lack of doctests). - 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 -~----------~----~----~----~------~----~------~--~---
