Metatables

Metamethods allow us to change the behavior of a table by writing custom functions for operators, such as comparing objects and arithmetical operations. For example, let’s say we would like to overload the add functionality of our table object with a new function that adds up certain field. Normally, the addition operation isn’t valid on tables, but we can overwrite the metamethod __add to perform whatever we need.

Arithmetic methamethods

The following are the methamethods available:

__add	Addition operator
__mul	Multiplication operator
__sub	Subtraction operator
__div	Division operator
__unm	Negation operator
__pow	Exponentiation operator
__concat	Concatenation...