Re: [Swig-user] Wrap python list to char**

[Vipul R. <vip...@gm...>]

Hi Stefan,

Thanks for your reply. But I am now getting the following error on compiling
the swig-generated .cxx file with g++ :

master_wrap.cxx: In function ‘PyObject*
_wrap_ossimInit_initialize__SWIG_0(PyObject*, PyObject*)’:
master_wrap.cxx:5916: error: ‘size’ was not declared in this scope
master_wrap.cxx:5917: error: ‘$2’ was not declared in this scope
master_wrap.cxx:5926: error: invalid conversion from ‘char*’ to ‘int’
master_wrap.cxx:5947: error: ‘$2’ was not declared in this scope
master_wrap.cxx: In function ‘PyObject*
_wrap_ossimIrect_getBounds(PyObject*, PyObject*)’:
master_wrap.cxx:21323: error: ‘size’ was not declared in this scope
master_wrap.cxx:21324: error: ‘$2’ was not declared in this scope
master_wrap.cxx:21333: error: invalid conversion from ‘char*’ to ‘int’
master_wrap.cxx:21353: error: ‘size’ was not declared in this scope
master_wrap.cxx:21354: error: ‘$2’ was not declared in this scope
master_wrap.cxx:21363: error: invalid conversion from ‘char*’ to ‘int’
master_wrap.cxx:21383: error: ‘size’ was not declared in this scope
master_wrap.cxx:21384: error: ‘$2’ was not declared in this scope
master_wrap.cxx:21393: error: invalid conversion from ‘char*’ to ‘int’
master_wrap.cxx:21413: error: ‘size’ was not declared in this scope
master_wrap.cxx:21414: error: ‘$2’ was not declared in this scope
master_wrap.cxx:21423: error: invalid conversion from ‘char*’ to ‘int’

I can't seem to figure it out. I have been trying my hand at this for quite
some time but couldn't get anywhere. Please help.

Thanks and regards,
Vipul

On Tue, Aug 9, 2011 at 6:15 PM, Stefan Zager <sz...@gm...> wrote:

> On Sat, Aug 6, 2011 at 3:05 AM, Vipul Raheja <vip...@gm...>
> wrote:
> >
> > Hi all,
> >
> > This question was asked on stackoverflow yesterday only, I am facing
> > the same problem.
> >
> > I am trying to access a C++ function from Python and I'm facing a
> > problem when I try to pass a Python list as an argument to a function.
> >
> > Here is the C++ function definition I'm trying to access (used to send
> > command to OSSIM reader) :
> >
> > ossimInit initialize(int& argc,           // No of arguments
> >                           char** argv)        // List of arguments
>
> For your method, you need a typemap that converts both the argc and
> argv arguments; following is modified from the SWIG docs:
>
> // This tells SWIG to treat char ** as a special case
> %typemap(in) int&, char ** (int size) {
>  /* Check if is a list */
>  if (PyList_Check($input)) {
>    size = PyList_Size($input);
>    $2 = &size;
>    int i = 0;
>    $1 = (char **) malloc((size+1)*sizeof(char *));
>    for (i = 0; i < size; i++) {
>      PyObject *o = PyList_GetItem($input,i);
>      if (PyString_Check(o))
>        $1[i] = PyString_AsString(PyList_GetItem($input,i));
>      else {
>        PyErr_SetString(PyExc_TypeError,"list must contain strings");
>        free($1);
>        return NULL;
>      }
>    }
>    $1[i] = 0;
>  } else {
>    PyErr_SetString(PyExc_TypeError,"not a list");
>    return NULL;
>  }
> }
>
> // This cleans up the char ** array we malloc'd before the function call
> %typemap(freearg) char ** {
>  free((char *) $1);
> }
>
>
> Stefan
>



-- 
*Vipul Raheja*
Senior Undergraduate
Computer Science and Engineering (Dual)
Lab for Spatial Informatics
IIIT Hyderabad