#8389: Sage eats all memory trying to evaluate MatrixSpace(QQ, 2)['x']
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Reporter: mmezzarobba | Owner: AlexGhitza
Type: defect | Status: needs_info
Priority: minor | Milestone: sage-6.1
Component: algebra | Resolution:
Keywords: | Merged in:
Authors: Michael Orlitzky | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Changes (by mmezzarobba):
* cc: nthiery (added)
Comment:
Replying to [comment:7 tscrim]:
> However what I'm thinking as a solution is that any parent in the
category of `Rings` should have a default `__getitem__` which checks for
string/list input and returns a polynomial/power series ring resp.
Thoughts?
In principle, I agree. Unfortunately, matrix spaces currently do not use
the category framework by default (one needs to call
`M.full_category_initialisation()` first) for efficiency reasons. So the
change you are suggesting would not solve the problem with matrix spaces
by itself.
And I'm honestly at lost as to how to use the category framework with
fundamental, widely used parents.
In our case, it would make sense (despite the issue with matrix rings) to
move the definition of `__getitem__` that deals with polynomials rings and
the like from `sage.structure.Rings` to
`sage.category.rings.Rings.ParentMethods`. But many common rings do not
descend from `Rings().parent_class`, so one would need a wrapper in one
direction or the other. Since `Rings.ParentMethods` is supposedly the
recommended place to add generic stuff for rings in the long run, it would
be natural to move the implementation there and provide a compatibility
wrapper in `Ring`. Except that `Ring` comes before `Rings.ParentMethods`
in the MRO of (most?) rings that use both...
(On the top of that, there is a hack in `Parent.__getitem__` that one
needs to be careful not to break...)
--
Ticket URL: <http://trac.sagemath.org/ticket/8389#comment:9>
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