This example tests SWIG's handling of C++ references. Since C++ references are closely related to pointers (as both refer to a location in memory), SWIG simply collapses all references into pointers when creating wrappers.
Vector operator+(const Vector &a, const Vector &b) {
   Vector result;
   result.x = a.x + b.x;
   result.y = a.y + b.y;
   result.z = a.z + b.z;
   return result;
}
or a function:
Vector addv(const Vector &a, const Vector &b) {
   Vector result;
   result.x = a.x + b.x;
   result.y = a.y + b.y;
   result.z = a.z + b.z;
   return result;
}
In these cases, SWIG transforms everything into a pointer and creates a wrapper
that looks like this:
Vector wrap_addv(Vector *a, Vector *b) {
    return addv(*a,*b);
}
Occasionally, a reference is used as a return value of a function
when the return result is to be used as an lvalue in an expression.
The prototypical example is an operator like this:
or a method:Vector &operator[](int index);
For functions returning references, a wrapper like this is created:Vector &get(int index);
Vector *wrap_Object_get(Object *self, int index) {
    Vector &result = self->get(index);
    return &result;
}
The following header file contains some class
definitions with some operators and use of references.
class VectorArray {
public:
 ...
   %extend {
    Vector &get(int index) {
      return (*self)[index];
    }
    void set(int index, Vector &a) {
      (*self)[index] = a;
    }
   }
   ...
}
Click here to see a SWIG interface file with these additions.