php inheritance interface type declarations

inheritance-type-declarations.php

<?php
interface iInvokable {
    function __invoke($arg = null);
}

interface iResponder extends iInvokable {
    /** Bind next responder */
    function then(iInvokable $responder);
}

class Responder implements \iResponder {

    function __invoke($arg = null)
    {
        // TODO: Implement __invoke() method.
    }

    /** Bind next responder */
    function then(iInvokable $responder)
    {
        // TODO: Implement then() method.
    }
}

class OtherResponder implements \iResponder {

    function __invoke($arg = null)
    {
        // TODO: Implement __invoke() method.
    }

    /** Bind next responder */
    function then(iInvokable $responder)
    {
        // TODO: Implement then() method.
    }
}

class Invokable implements \iInvokable {

    function __invoke($arg = null)
    {
        // TODO: Implement __invoke() method.
    }
}

$responder = new Responder();
$responder->then(new OtherResponder());
$responder->then(new Invokable());
?>