| Add | the addition (+) operation. If any operand for an
addition is not a number (nor a string coercible to a
number), Lua will try to call a metamethod. First, Lua will
check the first operand (even if it is valid). If that
operand does not define a metamethod for __add, then Lua
will check the second operand. If Lua can find a
metamethod, it calls the metamethod with the two operands
as arguments, and the result of the call (adjusted to one
value) is the result of the operation. Otherwise, it raises
an error. |
| Sub | the subtraction (-) operation. Behavior similar to the
addition operation. |
| Mul | the multiplication (*) operation. Behavior similar to the
addition operation. |
| Div | the division (/) operation. Behavior similar to the
addition operation. |
| Mod | the modulo (%) operation. Behavior similar to the
addition operation. |
| Pow | the exponentiation (^) operation. Behavior similar to the
addition operation. |
| Unm | the negation (unary -) operation. Behavior similar to the
addition operation. |
| Idiv | the floor division (//) operation. Behavior similar to
the addition operation. |
| Band | the bitwise AND (&) operation. Behavior similar to the
addition operation, except that Lua will try a metamethod
if any operand is neither an integer nor a value coercible
to an integer (see §3.4.3). |
| Bor | the bitwise OR (|) operation. Behavior similar to the
bitwise AND operation. |
| Bxor | the bitwise exclusive OR (binary ~) operation. Behavior
similar to the bitwise AND operation. |
| Bnot | the bitwise NOT (unary ~) operation. Behavior similar to
the bitwise AND operation. |
| Shl | the bitwise left shift (<<) operation. Behavior similar
to the bitwise AND operation. |
| Shr | the bitwise right shift (>>) operation. Behavior
similar to the bitwise AND operation. |
| Concat | the concatenation (..) operation. Behavior similar to
the addition operation, except that Lua will try a
metamethod if any operand is neither a string nor a number
(which is always coercible to a string). |
| Len | the length (#) operation. If the object is not a string,
Lua will try its metamethod. If there is a metamethod, Lua
calls it with the object as argument, and the result of the
call (always adjusted to one value) is the result of the
operation. If there is no metamethod but the object is a
table, then Lua uses the table length operation (see
§3.4.7). Otherwise, Lua raises an error. |
| Eq | the equal (==) operation. Behavior similar to the
addition operation, except that Lua will try a metamethod
only when the values being compared are either both tables
or both full userdata and they are not primitively equal.
The result of the call is always converted to a boolean. |
| Lt | the less than (<) operation. Behavior similar to the
addition operation, except that Lua will try a metamethod
only when the values being compared are neither both
numbers nor both strings. The result of the call is always
converted to a boolean. |
| Le | the less equal (<=) operation. Unlike other operations,
the less-equal operation can use two different events.
First, Lua looks for the __le metamethod in both
operands, like in the less than operation. If it cannot
find such a metamethod, then it will try the __lt
metamethod, assuming that a <= b is equivalent to not (b <
a). As with the other comparison operators, the result is
always a boolean. (This use of the __lt event can be
removed in future versions; it is also slower than a real
__le metamethod.) |
| Index | The indexing access operation table[key]. This event
happens when table is not a table or when key is not
present in table. The metamethod is looked up in table. |
| Newindex | The indexing assignment table[key] = value. Like the
index event, this event happens when table is not a table
or when key is not present in table. The metamethod is
looked up in table. |
| Call | The call operation func(args). This event happens when
Lua tries to call a non-function value (that is, func is
not a function). The metamethod is looked up in func. If
present, the metamethod is called with func as its first
argument, followed by the arguments of the original call
(args). All results of the call are the result of the
operation. (This is the only metamethod that allows
multiple results.) |
| Tostring | The operation used to create a string representation of
the object. |
| Pairs | the operation of iterating over the object's key-value
pairs. |
| CustomOperation Name | a custom operation, with the metamethod name as
parameter. |