<?php


trait AbsTrait
{
    private $a;
    private $b;
    private $c;

    function __construct()
    {
        $this->a = $this->b = $this->c = '';
    }
}

abstract class AbsClass
{
    use AbsTrait;
}


class Returner
{
    public static function getAbstractClass()
    {
        return (new class extends AbsClass {
            public function echo(string $str)
            {
                echo $str;
            }
        });
    }
}
echo '<pre>';
$class = Returner::getAbstractClass();
$obj = new $class();
var_dump($obj);
$obj->Echo('123');

$destroyer = function () use (&$obj) {
    var_dump($obj); // OK
    unset($obj);
    var_dump($obj); // NULL
};

$obj->EcHo('123');

$destroyer(); // CALL UNSET

$obj->ECHO('123'); // OK

var_dump($obj);