How to write a SWIG wrapper that overloads the CGAL Point_3 primitive.

[Willie Maddox]

Sebastien,

Currently, the Point_3 constructor takes 3 arguments each of type double,

pt = Point_3(x,y,z)

I want to overload this constructor to take a single variable,

pt = Point_3(a)

where "a" is a python tuple (or list) of length 3.

Now, I know I can simply do,

pt = Point_3(*a)

but that would defeat the point of this exercise.

There is an example in the SWIG (version 3, chapter 36.9.4) documentation that looks like a good place to start. Modifying this example to take a 3-tuple instead of a 4-tuple, we have:

%define SWIG_CGAL_tuple_to_Point_3

%typemap(in) double[3] (double temp[3]) {

  int i;

  if (PyTuple_Check($input)) {

    if (!PyArg_ParseTuple($input,"ddd",temp,temp+1,temp+2)) {

      PyErr_SetString(PyExc_TypeError,"tuple must have 3 elements");

      return NULL;

    }

    $1 = &temp[0];

  } else {

    PyErr_SetString(PyExc_TypeError,"expected a tuple.");

    return NULL;

  }

}

%enddef

I put this script in Python/typemaps.i and in CGAL_Kernel.i I add the following just after line 16:

%import  "SWIG_CGAL/Common/Macros.h" // line 15

%import  "SWIG_CGAL/Common/Iterator.h" // line 16

#ifdef SWIGPYTHON

%include "SWIG_CGAL/Python/typemaps.i"

SWIG_CGAL_tuple_to_Point_3

#endif

It is not obvious to me, however, how to overload the constructor in Point_3_decl.h.  Specifically, if I use,

Point_3(ARG):data(arr[0],arr[1],arr[2]){}

what should ARG be?

Thanks,

-Will

[Willie Maddox]

Nevermind, I figured it out. :)