PHP Forcing Class Var to have a specific type

<?php 
/*
*  A way to to type cast objects before php7
*/
class test{

    private $string   = array('typeof' => 'string', 'value' => null);
    private $int      = array('typeof' => 'integer', 'value' => null);
    private $double   = array('typeof' => 'double', 'value' => null);
    private $testObj  = array('typeof' => 'test', 'value' => null);

    public function __get($name)
    {
        return $this->{$name}['value'];
    }
    public function __set($var, $val)
    {
        $cast = $this->{$var}['typeof'];
        
        if( gettype($val) === $cast || (gettype($val) === 'object' && get_class($val) === $cast))
        {
            $this->{$var}['value'] = $val;
        }
        else 
        {
            trigger_error('$'.$var . " must be of type ". $this->{$var}['typeof']);
        }
    }

}

$test = new test();

$test->string = "100";
$test->int = 100;
$test->double = 100.00;
$test->testObj = $test;