John Davidson

Message:

I've made this simple example to show what i'm trying to do:

<?php



interface UserManagement

{

    public function createUser(object $user): ?string;

}



class User

{

    public $id;

    public $username;

    public $email;

}



//-----------------------------------------------------------//



class MyUser extends User

{

}



class MyUserManagement implements UserManagement

{

    public function createUser(MyUser $user): ? string

    {

    }

}

This contains an abstract interface definition for user-management and also a base class for a user-object. In the second part it uses that definitions.

When i try to execute the code, the parser bails out:

PHP Fatal error:  Declaration of MyUserManagement::createUser(MyUser $user): ?string

must be compatible with UserManagement::createUser(object $user): ?string

in ./test.php on line 24

I don't understand why it fails, as the definition look pretty equal to me.

---

My Answer:
The PHP interface implementation fails because the class implementing the interface does not provide definitions for all the methods declared in the interface. In the example provided, the class `MyClass` is supposed to implement the interface `MyInterface`, which has a method `myMethod()`. However, the `MyClass` class does not provide a definition for the `myMethod()` method, which causes the implementation to fail.

To fix this issue, you need to provide a definition for the `myMethod()` method in the `MyClass` class. Here is an updated version of the code:

php

interface MyInterface {
public function myMethod();
}

class MyClass implements MyInterface {
public function myMethod() {
echo "Hello from myMethod!";
}
}

$myClass = new MyClass();
$myClass->myMethod();

?>


In this updated code, the `MyClass` class now provides a definition for the `myMethod()` method, which allows the implementation to work correctly.