PHP: "Declaration of ... should be compatible with that of ..."

Question

I'd like to create an interface for entities that are CRUDable (can be saved and deleted). Here is my abstract class:

abstract class AbstractCrudableEntity extends AbstractEntity
{
    abstract public function doSave();
    abstract public function doDelete();
}

My implementing class needs a couple extra parameters to those methods. Here is the signature of the implementing class:

class Contact extends AbstractCrudableEntity {
    public function doSave(User $user, \UberClientManager $manager);
    public function doDelete(User $user, \UberClientManager $manager);
}

I understand that PHP requires that implementing classes have the same parameters for the methods as the parent class (there are several questions that answer this question: this, for example). So that is not the problem.

However, I recently came across some code in Symfony dealing with authentication tokens. The class UsernamePasswordToken extends AbstractToken, and has a different set of parameters in the __construct() method: AbstractToken::__construct() versus UsernamePasswordToken::__construct().

My question is how is Symfony able to do this? What is the difference between this and my code?

Answer 1

Overriding constructors is a special case:

Unlike with other methods, PHP will not generate an E_STRICT level error message when __construct() is overridden with different parameters than the parent __construct() method has.

You can not do that with other methods.