<form method="POST">
    <h3>Editing: ObjectType.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php declare(strict_types=1);
/*
 * This file is part of sebastian/type.
 *
 * (c) Sebastian Bergmann &lt;sebastian@phpunit.de&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace SebastianBergmann\Type;

use function is_subclass_of;
use function strcasecmp;

final class ObjectType extends Type
{
    /**
     * @var TypeName
     */
    private $className;

    /**
     * @var bool
     */
    private $allowsNull;

    public function __construct(TypeName $className, bool $allowsNull)
    {
        $this-&gt;className  = $className;
        $this-&gt;allowsNull = $allowsNull;
    }

    public function isAssignable(Type $other): bool
    {
        if ($this-&gt;allowsNull &amp;&amp; $other instanceof NullType) {
            return true;
        }

        if ($other instanceof self) {
            if (0 === strcasecmp($this-&gt;className-&gt;qualifiedName(), $other-&gt;className-&gt;qualifiedName())) {
                return true;
            }

            if (is_subclass_of($other-&gt;className-&gt;qualifiedName(), $this-&gt;className-&gt;qualifiedName(), true)) {
                return true;
            }
        }

        return false;
    }

    public function name(): string
    {
        return $this-&gt;className-&gt;qualifiedName();
    }

    public function allowsNull(): bool
    {
        return $this-&gt;allowsNull;
    }

    public function className(): TypeName
    {
        return $this-&gt;className;
    }

    /**
     * @psalm-assert-if-true ObjectType $this
     */
    public function isObject(): bool
    {
        return true;
    }
}
</textarea><br>
    <input type="submit" value="Save">
</form>