Actually that example helps. My understanding is that setting facade=True allows the elements to have arbitrary objects, necessarily even elements. For example:
sage: S = FiniteEnumeratedSet([1, Permutation([1,3,2]), Word('a')]); S {1, [1, 3, 2], word: a} sage: S[0].parent() Integer Ring sage: S[1].parent() Traceback ... AttributeError: 'Permutation_class' object has no attribute 'parent' sage: S[2].parent() Words Perhaps it would be better it would be better to set _facade_for = facade in parent.pyx by un-indenting the line one step in Parent.__init__() rather than doing a getattr(). I'll also write a quick patch updating the documentation for facade parents explaining the facade True. Thanks, Travis On Wednesday, December 5, 2012 11:51:45 PM UTC-8, Vincent Delecroix wrote: > > An example in sage.sets.finite_enumerated_set. But an example is not > an explanation ;-) > > 2012/12/6 Travis Scrimshaw <tsc...@ucdavis.edu <javascript:>>: > > What is the reason why facade=True is allowable by Parent? It seems > like > > we always want to pass in the parent(s) which our facade parent is > acting > > for. > > > > On Wednesday, December 5, 2012 8:23:01 AM UTC-8, Vincent Delecroix > wrote: > >> > >> I just upload on trac a patch about the initialisation of facade sets > >> at #13801. One of the smallest patch I never write... which corrects > >> two errors. > >> > -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To view this discussion on the web visit https://groups.google.com/d/msg/sage-combinat-devel/-/imT4IVSUpfMJ. 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.