#17096: Implement categories for filtered algebras
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Reporter: tscrim | Owner: tscrim
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: categories | Resolution:
Keywords: filtered algebras | Merged in:
Authors: Travis Scrimshaw | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/categories/filtered_algebras-17096|
b29f67e46e18721313330d3a6e116cf3df2eaf8e
Dependencies: | Stopgaps:
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Comment (by nbruin):
Replying to [comment:42 tscrim]:
> Yes, that's correct (although it could be subclasssed but that's not my
intent when I designed it). However it doesn't need to be a cached method
because everything comes along for the ride from the category (and it
should return an equal object every time). Nils, does this lead to a
memory leak when a `@cached_method` return a `UniqueRepresentation`? I
think it does but I don't remember...
Quite possibly. See [http://trac.sagemath.org/ticket/14356#comment:6
#14356 comment 6] and
[https://groups.google.com/forum/#!msg/sage-
devel/q5uy_lI11jg/CB15fcRmE4cJ]
The main thing to watch out for is caching on an object A a
!UniqueRepresentation object B that has A as a construction parameter.
As pointed out in the referenced comment, one is usually in the clear if
the construction parameters of a !UniqueRepresentation are fundamentally
simpler than the object itself. I'd say that fails for
!AssociatedGradedAlgebra if that takes an algebra it's isomorphic to as an
ungraded algebra as construction parameter! I would consider making it a
factory and construct from only the base ring, generator names, grading
information etc. and then link it via the coercion framework/cached
methods. Then at least it's clear that strong references are held locally.
It's important to realize that !UniqueRepresentation has a serious cost
associated with it.
--
Ticket URL: <http://trac.sagemath.org/ticket/17096#comment:44>
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