Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:92468
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 74.125.82.46 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>
Message-ID: <57164889.1080609@gmail.com>
Date: Tue, 19 Apr 2016 16:02:33 +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: <57164550.7070008@zend.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)

Dmitry Stogov wrote on 19/04/2016 15:48:
> callable-type is much simpler solution for this use-case.
> Usage of Interfaces to check function prototypes is a bit tricky, but 
> yes, this is a possible use-case.
> Do you like to work with framework, that use this trick for every 
> callback? 

If you don't use __invoke as the function name, you can have a single 
class implement multiple contracts, e.g. to register for more than one 
event type with different signatures.

I guess if you had callable-types *and* union types, you could get the 
best of both worlds:

interface UserEventCallbackInterface {
     public function handleUserEvent(UserEvent $event): boolean;
}
public function registerCallback(EventCallbackInterface|callable(Event): 
boolean $handler) { ... }

The implementation has to be a bit fiddlier here, because you need to 
sometimes call $handler->handleUserEvent($event) and sometimes 
$handler($event); with a functional interface, the engine makes 
$handler->handleUserEvent($event) work for you. The cost is that the 
call site has to be a bit more verbose to specify the interface, rather 
than implicitly meeting the contract.

Regards,
-- 
Rowan Collins
[IMSoP]