>> Will the circular references "functionspace <->
>> testfunction" be a problem for garbage collection?
>
> Yes.

I am not familiar with the particulars here, but the circular
references are only a problem if the objects have custom deleters
(__del__ methods). Swig likes to generate (empty) __del__ methods, but
they can be disabled by the should-have-been-default flag
--noproxydel.

-j.

On 28 November 2012 20:03, Johan Hake <email address hidden> wrote:
> On 11/28/2012 07:15 PM, Martin Sandve Alnæs wrote:
>> I fixed this permanently by constructing both test and trial function
>> simultaneously on demand using Argument(V) and storing them to
>> V._argument_functions. Will the circular references "functionspace <->
>> testfunction" be a problem for garbage collection?
>
> Yes.
>
> I wonder how this can be implemented without some error prone
> heuristics. A robust, but quite intrusive way, would be to always
> instantiate a TestFunction together with a TrialFunction whenever one
> need the latter.
>
> Or one could introduce a trial and test space specific counter.
> Something like:
>
> class Argument(.):
>    _test_and_trial_counters = [dict(test=False, trial=False)]
>    ...
>
> class TestFunction(.):
>     def __init__(.):
>         .
>         counters = Argument._test_and_trial_counters
>         if counters[-1]["test"]:
>             counters.append(dict(test=False, trial=False))
>         counters[-1]["test"] = True
>         Argument(self, ., count=len(counters)*2)
>
> class TrialFunction(.):
>     def __init__(.):
>         .
>         counters = Argument._test_and_trial_counters
>         if counters[-1]["trial"]:
>             counters.append(dict(test=False, trial=False))
>         counters[-1]["trial"] = True
>         Argument(self, ., count=len(counters)*2-1)
>
> Johan
>
> --
> You received this bug notification because you are a member of DOLFIN
> Team, which is subscribed to DOLFIN.
> https://bugs.launchpad.net/bugs/1083720
>
> Title:
>   replace() fails if the new function spaces have a different mesh
>
> Status in DOLFIN:
>   Fix Committed
>
> Bug description:
>   I submit this bug report following Marie's suggestions on the related
>   DOLFIN question
>   (https://answers.launchpad.net/dolfin/+question/215120)
>
>   DOLFIN crashes in the solve() routine after using replace() to replace
>   the function spaces of a form.
>
>   While the solve succeeds if replaced function spaces have:
>   - a different polynomial degree or
>   - a different polynomial degree and a different mesh,
>   it does not work if the new function spaces is based on a new mesh only.
>
>   This is the error message I get:
>   *** -------------------------------------------------------------------------
>   *** Error: Unable to define linear variational problem a(u, v) = L(v) for all v.
>   *** Reason: Expecting the solution variable u to be a member of the trial space.
>   *** Where: This error was encountered inside LinearVariationalProblem.cpp.
>   *** ------------------------------------------------------------------------
>
>   The attached file demonstrates the problem.
>
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