Single type array class in PHP

List.php

<?php

final class List implements ArrayAccess
{

    protected $type;
    protected $array = [];

    function __construct($var)
    {
        $this->type = $this->getType($var);
    }

    protected function getType($var): string
    {
        $type = gettype($var);
        if ($type != 'object') {
            return $type;
        }

        return get_class($var);
    }

    public function offsetExists($offset)
    {
        return array_key_exists($offset, $this->array);
    }

    public function offsetGet($offset)
    {
        return $this->array[$offset];
    }

    public function offsetSet($offset, $value)
    {
        if($this->type != $this->getType($value)){
            $reflection = new ReflectionMethod($this, __FUNCTION__);
            throw new TypeError(sprintf(
                'Argument passed to %s must be an instance of %s, %s given on line %s',
                __class__,
                $this->type,
                $this->getType($value),
                $reflection->getStartLine()
            ));
        }
        $this->array[$offset] = $value;
    }

    public function offsetUnset($offset)
    {
        unset($this->array[$offset]);
    }
}