Copy constructor

[DimaMelnichenko]

Hi, thanks for the cool lib.
I have a question with a userdata objects.
For sample:
--lua code
"userdataObj = userdataObj + 2"
Code works fine with your wrapper. There is an overloaded operator __add, it is called well.
But this is called the copy constructor. How do I invoke the assignment operator instead?
Two construct objects is too much for this operation )))