I'm going to work on PETSc's dynamic libraries support

[Lisandro Dalcin]

After the discussion about mapping cookies to Python types (let's
continue on int in the near future), I realized that petsc4py was
actually broken in for the case of PETSc's configure.py
--with-dynamic=1 !!!. Of couse, I've finally fixed all the problems,
now petsc4py can be built and used with any of static/shared/dynamic;
of course, in the static case, things get more restrictive (for
example, now easy way to use petsc4py+slepc4py+tao4py), so the
recommended way is to use at least shared libs.

After all that work, I've started to dive in the whole beast in PETSc
core, and I believe there is a lot of room for improvement.  So I'll
take this. Could someone of you wipe-out this repo and make in that
directory a fresh clone of petsc-dev?

http://petsc.cs.iit.edu/petsc/petsc-dev-dalcinl/


Now, the stuff I'm thinking we can improve:

1) Make a distintion between PETSC_USE_DYNAMIC_LIBRARIES (ie, PETSc
libs are intended to be dlopenable), and PETSC_HAVE_DYNAMIC_LIBRARIES
(PETSc libs are just static/shared, not intended for dlopen; but PETSc
CAN dlopen other  third-party libs).

2) Add appropriate typedefs for PestcDLHandle, an enumeration
PetscDLFlags, and routines PetscDLOpen, PetscDLClose, and PetscDLSym.
This would abstract the handling of the different dlopen-like family
of functions across platforms, in a way similar to what GNU libtool
does.

3) The above support for dlopening other libs will be available in
regardeless of PETSc libraries being static/shared/dynamic. The only
requisite for this to work is that
dlopen/LoadLibrary/other-dlopen-like-api is available. For all this,
perhaps I will need help for fixing BuildSystem in case this is
necessary.

4) And finally, try to use all the above stuff tome make possible
PETSc can dlopen the Python shared library and 'import' petsc4py.
Working harder, all this could even work with PETSc static libs, more
or less like you can build python with static libs, but the python
executable can still dlopen extension modules.

Now, I want to know your opinions...


-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
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