#10963: More functorial constructions
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Reporter: nthiery | Owner: stumpc5
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.1
Component: categories | Resolution:
Keywords: days54 | Merged in:
Authors: Nicolas M. Thiéry | Reviewers: Simon King, Frédéric
Report Upstream: N/A | Chapoton
Branch: | Work issues:
public/ticket/10963 | Commit:
Dependencies: #11224, #8327, | eb7b486c6fecac296052f980788e15e2ad1b59e4
#10193, #12895, #14516, #14722, | Stopgaps:
#13589, #14471, #15069, #15094, |
#11688, #13394, #15150, #15506 |
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Comment (by vbraun):
I agree with Simon's explanations. And it illustrates the point that I'm
trying to make, if you show the code to a Python programmer then he'll be
quite astonished that it does what it does since it seemingly consists
only of all a pile of apparently unrelated inner classes.
The question about unnecessary breaking of symmetry already arises at
{{{
class As(Category_singleton):
class B(CategoryWithAxiom):
class C(CategoryWithAxiom):
pass
}}}
why As.B.C and not As.C.B? The only difference is the internal
representation of the class. In particular, this explicitly specified
order is not used in the printing order of the category-with-axiom.
The asymmetry in specifying the relations is also in addition (and
unrelated) to the print sort order.
The only "error message" if you get the asymmetry wrong will be an
infinite recursion.
--
Ticket URL: <http://trac.sagemath.org/ticket/10963#comment:456>
Sage <http://www.sagemath.org>
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