Class Operator
Class operator is the ::class, added to a class, interface, trait or enumeration identifier. It returns the fully qualified name of the class, according to the current code.
::class is affected by use expressions, but not by class_alias() function.
<?php
// class operator in action
// This is an unknown class, so it displays A\B
echo A\B::class;
// This is an 'use' class, so it displays A\B
use A\B as D;
echo D::class;
// class_alias creates a new class, so it is different.
class E{}
class_alias('E', 'F');
echo F::class;
?>