#10963: More functorial constructions
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Reporter: nthiery | Owner: stumpc5
Type: enhancement | Status: needs_work
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: Detect and fix
public/ticket/10963 | Heisenbugs
Dependencies: #11224, #8327, | Commit:
#10193, #12895, #14516, #14722, | 8eaf51a82c4e2194769db13457979ae601ebbc04
#13589, #14471, #15069, #15094, | Stopgaps:
#11688, #13394, #15150, #15506 |
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Comment (by SimonKing):
Replying to [comment:263 nbruin]:
> Replying to [comment:261 SimonKing]:
> > No, it is not a memory leak. The stored items are formed by classes
that are defined in modules anyway.
>
> Not for things that get fed to it for which it's designed. Does it
always raise an error if it gets something else? It could leak that. So
(especially when you scribbe in the cache beforehand) you'll have to
ensure that the cache is cleansed of undesirable things.
That's what I do in the "finally" clause (which is never executed, as can
be seen by the absence of the warning message when starting Sage).
> Basically, the whole use of `base_category_class_and_axiom` is
questionable. Categories shoud just define a `_base_category_and_axiom`
attribute outright.
+1, because this would avoid headache.
-1, because this is what one would have to do in an abundance of
categories. This may even include (in the future?) categories that are
dynamically created.
Note that in addition to the lazy attribute,
`CategoryWithAxiom.__classget__` overrides
`cls._base_category_class_and_axiom`. So, why is there this lazy class
attribute?
I am not sure yet if I come to the same conclusions as you do. But I agree
that the relationship of these three things
- a lazy class attribute,
- a `__classget__` that as a side effect overrides the lazy class
attribute, and
- a cached function that calls the `__classget__` while it is computing
stuff for the lazy class attribute
should be straightened.
> As far as `base_category_class_and_axiom` is concerned, the value is a
function of only their name anyway. It's just a tool to save (a small
amount of) typing, and as we're seeing, causing nasty problems while
trying to do it.
Yes, for what we want to compute, it would be enough to let the input be
`cls.__name__`.
But no, ''if'' we want to make consistency checks (and in the current
implementation we do want consistency checks), then we need to input the
class.
--
Ticket URL: <http://trac.sagemath.org/ticket/10963#comment:265>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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