#12876: Fix element and parent classes of Hom categories to be abstract, and
simplify the Hom logic.
------------------------------------------------------------------------------------------------+
Reporter: nthiery
| Owner: nthiery
Type: enhancement
| Status: needs_review
Priority: major
| Milestone: sage-5.10
Component: categories
| Resolution:
Keywords: categories, Hom
| Work issues:
Report Upstream: N/A
| Reviewers: Simon King
Authors: Nicolas M. Thiéry
| Merged in:
Dependencies: #715, #11521, #12215, #12313, #13412, #13145, #14159, #13184,
#14287, #14217 | Stopgaps:
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Comment (by nthiery):
Replying to [comment:142 SimonKing]:
> Question: Is it really needed that each category defines its own
`HomCategory`, which in most cases is just
> {{{
> class HomCategory(HomCategory):
> pass
> }}}
> ?
>
> Since all classes for categories inherit from `Category`, couldn't one
just define the `HomCategory` there, and only replace it when really
needed?
Well, most categories actually don't define a HomCategory. I did not
strip the now trivial HomCategory in Schemes just as to avoid having
to fix some trivial doctest failures elsewhere (without it, a
Hom(scheme,scheme) was downgraded to the category of homsets of sets).
> This could be for a different ticket, though. I just wonder.
Yup. At this point we have very little use cases of HomCategories, and
I don't have a good view on how often this gadget will be used, and
thus what the sane default should be. So I would indeed leave things
untouched for now until we have more experience.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12876#comment:147>
Sage <http://www.sagemath.org>
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