Hi,
I'm wrapping a C++ library (http://www.box2d.org/). A python version done
with swig already exists, but I'm trying to make it more pythonic/cythonic,
and preparing it for a future project. It's all going well, and I'm having a
fun time -- cython rocks.
I have a few questions and thoughts about wrapping. Consider wrapping
something simple like this, where things are public:
class Vector2d {
public:
float x, y
Vector2d() : x(0.0), y(0.0) {}
// other useful stuff here
};
I begin by doing this:
extern from "vector2d.h":
cdef cppclass Vector2d:
float x, y
Vector2d()
Here are the questions:
1. Why must I use a *pointer* in my python class?
cdef class PythonVector2d:
cdef Vector2d *obj
There is a default constructor, and I can happily declare it on the stack in
a function. I'm sure I'm missing something here; is there some danger with
allowing this?
2. How hard would it be to automatically forward member access to a
contained cppclass? Consider the following nasty hack:
cdef class PythonVector2d:
cdef public float x, y
cdef Vector2d *obj
def __cinit__(self, x, y):
self.x = x
self.y = y
self.obj = <Vector 2d*>x
ok. That is a bit nasty (I'm sure someone can tell me lots of reasons why I
shouldn't do this). But it really makes things easy. I don't have to declare
all the properties independently. And when I need the cpp version, I just
pass around pointer.
Something like this would be nice:
cdef class PythonVector2d:
cdef Vector obj
properties:
public obj.x as x
public obj.y as y
Does this look crazy?
Cheers,
Brett
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