#11521: Memleak when resolving the action of Integers on an Elliptic Curve
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Reporter: jpflori | Owner: robertwb
Type: defect | Status: needs_work
Priority: major | Milestone: sage-4.8
Component: coercion | Keywords: sd35
Work_issues: | Upstream: N/A
Reviewer: | Author: Simon King
Merged: | Dependencies: #11900 #715
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Comment(by jpflori):
Replying to [comment:97 SimonKing]:
> Yes, but then I don't understand why there is no error: In some places,
the coercion model tests for identity, and raises a big fat "coercion BUG"
otherwise.
I'll have a look at it, I'm not completely up to what the coercion model
actually does :)
I guess the doc could also be extended on that :)
>
> > The weakref domain and codomain in functors problem could be tackled
by adding an optional parameter for the use of weakref.
> >
> > By default, the behavior of functors would be as before with strong
refs (and the option to false).
> >
> > For the coercion models we would set the option to True and use
weakref whenever possible.
>
> Again, I believe that it must not be up to the user: "Evidently" (for a
human), the different copies of E in the while loop can be garbage
collected. It is our job to hammer the "evidence" into Sage. We shouldn't
simply say "let the user decide" whether he wants a leak or a potential
disaster: I would call it a disaster if one has an action and suddenly its
codomain is gone.
That would not really be up to the user if by default the functor does not
use weakref, but if we change this behavior for the coercion model by
switching the option.
It would be fatly documented not to set the option to True for general
use, so normal use would not lead to problems.
Of course it all depends on what you mean by "up to the user".
One could still intentionally set the option to true, and then cry that
its codomain disappeared...
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11521#comment:98>
Sage <http://www.sagemath.org>
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