Hey everyone, On Sunday, October 28, 2012 2:13:07 AM UTC-7, Andrew Mathas wrote: > > Hi Nicolas, > > Not OK (this could break e.g. Symmetric Functions): >> >> sage: Partitions().options(cmp=dominance) >> > > In his patch Travis has an option for changing the default comparison > method and I think that this would be useful. Below you also mention that > be able to change the default ordering for enumerating the elements is also > desirable but I can think of situations where this would break code. These > two examples suggest to me that the "not changing the semantic policy" may > be too strict. > > Having said this, one of the motivations behind my proposal is precisely > to avoid issues like this: as each option is available as a method of the > class, if external code wants or requires a particular variant of an > optional method then it should call that method directly. In this instance, > if the symmetric functions require the lexicographic ordering then they > should explicitly call the corresponding methods, such as __le___lex__. I > admit that this would be slightly annoying in this case -- and also > decrease the readability of the code -- but if it was agreed that cmp > methods should be optionable then this is how such problems would be dealt > with using the framework that I am proposing. > > I would want to extend the framework to also allow for setting options >> for the parent itself. Things like Partitions(3, order=...) that would >> change the enumeration order. >> > > Currently I have the parents controlling the parents but I guess that > there is no reason not to make the elements responsible for their own > options and the parents responsible for theirs. Alternatively, with some > hacking the options method of the parent could be made to recognise whether > it was a parent or element_class option. >
I believe we should allow individually created parents to set their options only via Partitions(3, order=...), that way we don't have to worry about changing something by surprise if something is a UniqueRepresentation. However by implementing this, we could then not break things by not necessarily having to call particular methods directly. So in SymmetricFunctions, if we need lex order, we call P = Partitions(3, order='lex') and then iterate over P. (Hopefully that makes sense...) > > - Element classes may be shared between different parents. One needs >> to make sure that one does not affect by accident unrelated parents. >> > > Don't elements always have unique parents? Although I guess this issue > does arise because of inheritance with, for example, some methods for > StandardTableau being inherited from Tableau...there could be issues here. > Perhaps the factory framework for such classes that Florent is developing > would help here? > We have the following situation: class ElementFoo(Element): class Parent1(Parent): Element = ElementFoo class Parent2(Parent): Element = ElementFoo > > >> - Assigning methods to the class won't work with Cython classes (as >> far as I remember). >> > > I have no experience with cython yet but I wouldn't have thought this was > a big problem because all that I am really doing to using optionable > methods as aliases for the real methods. The idea is that a method like > _repr_ simply becomes an alias for _repr_with_option and that changing an > option for _repr_ just changes which function it is an alias for. > Couldn't we just do that with function pointers? http://docs.cython.org/src/reference/language_basics.html > > A related question: should this framework be about Parents or > SageObjects ... > > Given your comments about parents above, perhaps this should be generally > about objects...however, I am not sure how well what I am proposing will > work with multiple inheritance. This could definitely be a problem. > >From looking at it, the only problem I see with (multiple) inheritance might be making sure the display_options is coherent. Vincent, if I understand you correctly you're trying to avoid polluting the namespace of the element classes. This also makes me worry about the following situation. Suppose Elt is an element to 2 different parents Foo and Bar where the repr for Foo.Elt is (naturally) different from Bar.Elt. Thus Foo.Elt.options(repr=bar_repr) should throw an error. Best, Travis -- 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/-/GquWXCpCGs4J. 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.
