Power function as an operator.

[datibbaw]

This PR complements the pow-operator proposal, which has been accepted for 5.6

The power operator allows expressions, like:

echo 2 ** 3; // 8
$x = 2;
echo $x **= 3; // 8

It also supports GMP overloading:

$x = gmp_init(2) ** 3;
var_dump($x instanceof GMP); // bool(true)

[bukka]

Just quick question! What's the associativity for the gmp overloaded operator?

[bukka]

Looks like left assoc for gmp and right for num op?

[datibbaw]

@bukka Now, you know that doesn't make sense right? An operator doesn't change associativity when the operand types change ;-)

echo gmp_init(2) ** gmp_init(3) ** gmp_init(2); // 512

[bukka]

yeah my bad!