pycxx and multiple new types

John Hunter jdhunter at ace.bsd.uchicago.edu
Sun May 9 12:52:26 EDT 2004



I have been using pycxx 5.2.2 to write an extension module which
defines two new types, Point and Bbox.  The Bbox is constructed with 2
Point instances

class Point: public Py::PythonExtension<Point> ...

class Bbox: public Py::PythonExtension<Bbox> {
public:
  Bbox(Point& ll, Point& ur) : _ll(ll), _ur(ur) {};
  static void init_type(void);

  // return lower left point
  Py::Object ll(const Py::Tuple &args) { return Py::Object(&_ll); }

  // return upper right point
  Py::Object ur(const Py::Tuple &args) { return Py::Object(&_ur); }
  
private:
  Point& _ll, _ur;
};


The problem I am having is that if I instantiate a Bbox from 2 point
instances, my python test code hangs after the last line of the script
and doesn't return the shell prompt until I hit CTRL-C.

ll = Point(10, 10)
ur = Point(20, 20)
bbox = Bbox(ll, ur)  # this line causes the hang.

I think this is because I am not handling the ref count of the Point
objects properly.

My new_bbox function looks like


Py::Object _transforms_module::new_bbox (const Py::Tuple &args)
{
  
  args.verify_length(2);
  
  Point::check(args[0]);
  Point::check(args[1]);
  
  Point* ll = (Point*)(args[0].ptr());
  Point* ur = (Point*)(args[1].ptr());
  return Py::asObject(new Bbox(*ll, *ur) );  
}

Do you have any thoughts on what I am doing wrong?

Thanks,
John Hunter





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