Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:92471
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 74.125.82.51 as permitted sender)
To: internals@lists.php.net
References: <CAL=_i_mzF5U4kb487igLrMPvnK5UUNP0W1FA+MYHWMjmypJ3Cg@mail.gmail.com>
 <BY2PR0201MB1784951F449DA564BF12AE3DBF6C0@BY2PR0201MB1784.namprd02.prod.outlook.com>
 <CAL=_i_mxPnzm4O7mpVFiGTtxnwDSUtpzM7f8Su=LwkHTa_agOw@mail.gmail.com>
 <CAL=_i_nJrbCaN4RC0HrV8t4a07ugwG-j373wocaidNfJtWAKNA@mail.gmail.com>
 <5716310B.4060104@zend.com>
 <CAL=_i_mriQQ_MKEw-zm_xfJh5tYb6_nzE6iLMXh0zYEuWG_OiQ@mail.gmail.com>
 <57163CB0.70608@zend.com> <5716410C.1080904@gmail.com>
 <57164550.7070008@zend.com> <57164889.1080609@gmail.com>
 <57164CE8.4090307@garfieldtech.com>
Message-ID: <57164FBE.4070206@gmail.com>
Date: Tue, 19 Apr 2016 16:33:18 +0100
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101
 Thunderbird/38.7.2
MIME-Version: 1.0
In-Reply-To: <57164CE8.4090307@garfieldtech.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] RFC: Functional Interfaces
From: rowan.collins@gmail.com (Rowan Collins)

Larry Garfield wrote on 19/04/2016 16:21:
> Which is why I'm not sure I like that approach, because the place I 
> then call $handler needs to have a conditional in it.  There's another 
> RFC that was posted to Twitter but hasn't made it to the list yet that 
> seems to solve this better:
>
> https://wiki.php.net/rfc/callable-types

I'm not sure which approach you mean, but in Joe's proposal, you always 
call $handler as though it was an object implementing the interface; 
have a look at the ILog example in the RFC.

With a typed callable, you can always invoke as $handler(...) will work, 
but the implementer can't create an object that meets more than one 
contract, because they can only provide one __invoke method.


interface UserEventCallbackInterface {
     public function handleUserEvent(UserEvent $event): boolean;
}
interface CommentEventCallbackInterface {
     public function handleCommentEvent(CommentEvent $event): boolean;
}

class Logger implements UserEventCallbackInterface, 
CommentEventCallbackInterface { ... }
$logger = new Logger;

$simple_user_handler = function(UserEvent $event) implements 
UserEventCallbackInterface: boolean { ... }


In Joe's proposal, $logger and $simple_user_handler can be used 
interchangeably by calling $handler->handleUserEvent(...); the receiving 
code doesn't need to do anything special to accept the closure form, 
because the engine transforms it into the required object.

Regards,
-- 
Rowan Collins
[IMSoP]