Squirrel

// ogre Vector3 has overloaded operators for +, I only paste the relevant parts

namespace Ogre
{
class _OgreExport Vector3
{
public:
   Real x, y, z;
public:
   inline Vector3(){}
   inline Vector3( const Real fX, const Real fY, const Real fZ )
      : x( fX ), y( fY ), z( fZ )
   {}

   inline Vector3 operator + ( const Vector3& rkVector ) const
   {
      return Vector3(x + rkVector.x,y + rkVector.y,z + rkVector.z);
   }
};

SQClassDef <Ogre::Vector3> ("Vector3")

.overloadConstructor <Ogre::Vector3(*)(void)>()
.overloadConstructor <Ogre::Vector3(*)(float, float, float)>()
.overloadConstructor <Ogre::Vector3(*)(const Ogre::Vector3&)>()

.var (&Ogre::Vector3::x, "x")
.var (&Ogre::Vector3::y, "y")
.var (&Ogre::Vector3::z, "z")

.overloadOperator <Ogre::Vector3(Ogre::Vector3::*)(const Ogre::Vector3&) const>(&Ogre::Vector3::operator+, "_add");

// script that fails

 local result = Vector3 ();
 result = v + vcopy;  // both v and vcopy are Vector3

//#define SQPLUS_SUPPORT_NULL_INSTANCES

#include <sqplus.h>