On Wed, Mar 10, 2010 at 3:49 PM, Ondrej Certik <[email protected]> wrote:
> On Wed, Mar 3, 2010 at 6:23 PM, Lisandro Dalcin <[email protected]> wrote:
>> On 3 March 2010 23:08, Ondrej Certik <[email protected]> wrote:
>>>>
>>>> Am I being clear enough?
>>>
>>> Yes, that is clear to me, thanks.
>>>
>>
>> OK. Once you have something working, let's polish it and ask other for
>> opinions, then push to cython-devel.
>
> If I go the global Python() class route, I would need to generate the
> Python() class automatically, since the list of my Cython functions
> can be quite long, so I don't want to keep updating the Python class
> interface by hand.
>
> So I am probably going to take the combination of both approaches that
> you suggested:
>
> 1) implement the global Python() class, that takes care of execution
> contexts, initializing python and the Cython API and has the following
> methods:
>
> void cmd(const char*) // runs a Python command in the (possibly local)
> context/namespace
> void insert_object(const char*, PyObject *) // inserts a Python object
> into the context/namespace
> PyObject *get_object(const char*) // gets a Python object from the context
>
> 2) the helper functions for doing the actual conversion to and from Python
> like:
>
> static PyObject *(*c2py_CooMatrix)(struct CooMatrix *);
> static PyObject *(*c2py_CSRMatrix)(struct CSRMatrix *);
> static PyObject *(*c2py_int)(int);
> static int (*py2c_int)(PyObject *);
> static char *(*py2c_str)(PyObject *);
> static double (*py2c_double)(PyObject *);
> static PyObject *(*c2numpy_int)(int *, int);
> static PyObject *(*c2numpy_int_inplace)(int *, int);
> static PyObject *(*c2numpy_double)(double *, int);
> static PyObject *(*c2numpy_double_inplace)(double *, int);
> static void (*numpy2c_int_inplace)(PyObject *, int **, int *);
> static void (*numpy2c_double_inplace)(PyObject *, double **, int *);
> .... [way more]
Here is how it would be used:
in the main.cpp:
#include "python_api.h"
int main(int argc, char* argv[])
{
python = Python(argc, argv);
}
and then somewhere else in the C++ program, like linsystem.cpp:
#include "python_api.h"
...
python.cmd("print 'ok'");
python.insert_object("i", c2py_int(5));
python.cmd("i += 5");
int i = py2c_int(python.get_object("i"));
// i == 10 now
...
This assumes that "python" is a global variable, that is defined in my
project only, e.g. then the user can define it locally for each class
that needs to access python. And then, when I expose more of my
functionality either from C or from Python, I just add more c2py_* and
py2c_* methods in the .pyx file and that's it.
Ondrej
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