On Friday, January 22, 2016 at 1:03:59 AM UTC-6, Nathann Cohen wrote: > > > Do you want DiGraph to have methods like rank or is_chain? > > Of course not. The idea was to have Poset carry a DiGraph > _hasse_diagram instead of a HasseDiagram object, and to [move/merge] > the methods from HasseDiagram with their Poset counterparts. > > > Also, by > > implementing them directly into the Poset's class, you must deal with > the > > elements labels at each computation, not just when you're moving to/from > the > > HasseDiagram backend. > > It is the same right now: you mut translate the elements in the Poset > function which calls the HasseDiagram function. Except when the > function does not care, like 'rank'. > > > this would require a > > lot more interaction converting between the two different > representations. > > At least with the HasseDiagram, which is a DiGraph, it reduces the > amount of > > overhead with this. > > I do not see how: this would happen as often, but it would happen in > the same location. Right now we write Poset functions whose only > purpose is to relabel elements before calling HasseDiagram methods. > This could be done at the same place. > > > Moreover, the methods in Poset should just be a wrapper > > around such functions in HasseDiagram (unless there is no apparent > penalty > > for directly implementing them in Poset). > > Why do you say that it is how the *should* be? > > Suppose you have function A that calls function B a lot over a loop, and both of them can take advantage of the canonical labeling of the DiGraph. If you do not have a HasseDiagram class, then A would have to convert the canonical labeling, then convert back every time it called B, which would have to unconvert, do it's operation. With the HasseDiagram, the Poset class can just act as a translation layer, so you only have to convert each way at most once. You could have a method of Poset which is convert_to_canonical and convert_from_canonical (although I think it does it right now the faster way of copying one list comprehension around), but it is a much better design to have the HasseDiagram subclass of DiGraph. It is such a small amount more code you need to write, and there is very little complexity added. You should not be having anything in the HasseDiagram class really call stuff from the Poset, so everything has good locality too.
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