I was forgetting to give an example of the Python code I would like to write:
>>> from petsc4py import PETSc
... now some uninteresting code for building a PETSc.Mat python object ...
... the result will be a PETSc.Mat m object ....
... once created, if I write "m" and press RETURN, this is the output ...
>>> m
<petsc4py.PETSc.Mat object at 0xb7bea548>
... so, basically, I already have a PETSc Mat in Python, because it is
exposed by the petsc4py package ...
... Now I want to pass this Python object to my "print_Mat" function ...
... What I'd like to write is ...
>>> form my_extension import *
>>> print_Mat(m)
I hope now it's all clear.
Thank you in advance.
Michele
2009/10/26 Michele De Stefano <micdestef...@gmail.com>:
> Ok. Let me clarify (I looked at the link you suggested, but I've not
> found the answers I was looking for).
>
> There exist a "petsc4py" package, which can be extended using its C
> API. This package, already exposes PETSc types (and also the Mat
> type). petsc4py is not programmed using Boost Python.
>
> Now, assume I already have a C++ function that takes a Mat parameter;
> to make it simple, let's take
>
> void print_Mat(Mat m) {
> ... // The implementation is not interesting
> };
>
> I'd like to expose this function to Python, with a seamless
> integration mechanism, using Boost Python.
>
> Unfortunately, if I use the petsc4py API, I have to expose a wrapper
> for "print_Mat", in this way:
>
> void print_Mat_Wrap(const object& mat_obj) {
> Mat m( PyPetscMat_Get(mat_obj.ptr()) );
> ... // The rest is not important
> }
>
> I don't know anything of the petsc4py implementation, but I know that
> it already exposes PETSc Mat to Python. I know also that, using the
> petsc4py C API, the only way to retrieve a Mat from a
> PyObject* is through the PyPetscMat_Get function, whose signature is this one:
>
> Mat (*PyPetscMat_Get)(PyObject *);
>
> I know for sure that Mat objects are not allocated with the C++ new
> operator (I don't know if this is a useful information for you).
>
> What I'd really like to do, would be to write a from-Python-converter
> from a PyObject* (containing a petsc4py exposed Mat) into a Mat, in
> order to be able to directly expose my "void print_Mat(Mat m)" without
> writing any wrapper ... but I didn't manage to properly make it ...
>
> Is this possible ?
>
>
> 2009/10/26 Randolph Fritz <rfritz...@gmail.com>:
>> Additional thought. Take a look at:
>> <http://wiki.python.org/moin/boost.python/PointersAndSmartPointers#OSGexample>
>> & see if it helps clarify some of the problems.
>>
>> --
>> Randolph Fritz
>> design machine group, architecture department, university of washington
>> rfr...@u.washington.edu -or- rfritz...@gmail.com
>>
>> _______________________________________________
>> Cplusplus-sig mailing list
>> Cplusplus-sig@python.org
>> http://mail.python.org/mailman/listinfo/cplusplus-sig
>>
>
>
>
> --
> Michele De Stefano
> http://www.linkedin.com/in/micdestefano
> http://xoomer.virgilio.it/michele_de_stefano
>
--
Michele De Stefano
http://www.linkedin.com/in/micdestefano
http://xoomer.virgilio.it/michele_de_stefano
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