dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

B1;2600;0cOn Wed, Feb 09, 2011 at 11:03:28PM +0000, Garth N. Wells wrote:
>
>
> On 09/02/11 22:43, Anders Logg wrote:
> > On Wed, Feb 09, 2011 at 10:11:40AM -0800, Johan Hake wrote:
> >> Hello!
> >>
> >> I am pretty sure the reason the Macbot still complains (mesh unit test) is
> >> that refine is broken for SWIG 2.0.
> >>
> >> I think it is some premature destruction of a refined mesh. I would suggest we
> >> implement a full shared_ptr version of the interface to get around this
> >> problem. I have no clue of why it works for SWIG 1.3.40. Probably because a
> >> faulty implementation.
> >>
> >> I also suggest more developers upgrade to SWIG 2.0.1 and maybe one of the
> >> linux build bots two? If it is only the Macbot that uses SWIG 2.0 it is easily
> >> to think it is some Mac specific error.
> >>
> >> Johan
> >
> > I plan to merge with main tomorrow if my buildbot is green. Then Marie
> > also needs to merge (we have both touched refine.h/cpp). Then we can
> > sort out the shared_ptrs.
> >
>
> I really don't get the approach to hierarchies. Mesh refinement was
> simple, and now something simple has become complex (with bugs that are
> hard to track down because of the introduced complexity).

I really don't understand what the problem is. Mesh refinement is just
as simple as it used to be, the Mesh class itself is (almost) as
simple as it used to be (one added inheritance), and the Hierarchical
base class is also a very simple class (just stores two pointers for
child and parent). All the complexity is in refine.cpp, which only
kicks in if you do something like refine(variational_problem) or
refine(function_space).

> This hierarchy business looks viral - now I get Swig warnings for
> DirichleBC.
>
> I would much rather keep basic classes simple, and have hierarchical
> containers that can keep track of parent/child relationships. The
> present approach seems to take a narrow/immediate view on the issue.

I think that would lead to more complex code. We would need to store
quite a few different relationship trees separately from the objects.

The problems we see now are related to SWIG and correct use of
shared_ptrs. We've had quite a few SWIG/shared_ptr problems in the
past and figured out how to fix them. I'm sure we will handle this
too.

--
Anders