reset.php

<?php
class Foo
{
    protected $bar;
    
    public function __construct()
    {
        $this->bar = 'bar';
    }
    
    public function __toString()
    {
        return $this->bar;
    }
    
    public function setBar($bar)
    {
        $this->bar = (string) $bar;
    }
}

$foo = new Foo;
print $foo;

$foo->setBar('baz');
print $foo;

$foo->__construct();
print $foo;

// barbazbar