rfc:protocol_type_hinting

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rfc:protocol_type_hinting [2013/06/26 16:43] – [Standards Based Interface Declarations] ircmaxellrfc:protocol_type_hinting [2017/09/22 13:28] (current) – external edit 127.0.0.1
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   * Date: 2013-06-25    * Date: 2013-06-25 
   * Author: Anthony Ferrara <ircmaxell@php.net>   * Author: Anthony Ferrara <ircmaxell@php.net>
-  * Status: Draft +  * Status: Withdrawn 
   * First Published at: http://wiki.php.net/rfc/protocol_type_hinting   * First Published at: http://wiki.php.net/rfc/protocol_type_hinting
  
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 } }
 class StaticLogger { class StaticLogger {
-    public static function log($message);+    public static function log($message) { /* blah */ }
 } }
 class OtherLogger { class OtherLogger {
-    public static function log($message, $bar);+    public static function log($message, $bar) { /* blah */ }
 } }
 Bar::foo(new FileLogger); // Good! Bar::foo(new FileLogger); // Good!
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 It also solves the triangular dependency problem since the sender never needs to explicitly require the dependency. That can be left for an off-line check (or a test), reducing the amount of and need for dependency resolving tools for the purpose of common interfaces... It also solves the triangular dependency problem since the sender never needs to explicitly require the dependency. That can be left for an off-line check (or a test), reducing the amount of and need for dependency resolving tools for the purpose of common interfaces...
 +
 +==== Trait Typing ====
 +
 +Currently, traits do not allow for specifying of typing information. And this is a good thing (it is by design).
 +
 +However, there are many times where we may wish to infer that the functionality presented by a trait is present in an object. An example would be Zend Framework's [[https://github.com/zendframework/zf2/blob/master/library/Zend/EventManager/ProvidesEvents.php|ProvidesEvents Trait]]. It basically looks like this:
 +
 +<file php ProvidesEvents.php>
 +<?php
 +namespace Zend\EventManager;
 +trait ProvidesEvents {
 +    protected $events;
 +    public function setEventManager(EventManagerInterface $events) { /* snip */ }
 +    public function getEventManager() { /* snip */ }
 +}
 +?>
 +</file>
 +
 +As the current system stands, classes that use the trait need to also implement a separate interface to get the message of the behavior across to the receiver that it supports events.
 +
 +With Structural Type Hinting, we can instead hint against the trait directly, which would require a class with the same public API that the trait provides, //irrespective of if it is actually using the trait or not//.
 +
 +<file php RequiresEvents.php>
 +<?php
 +function triggerEvent(<Zend\EventManager\ProvidesEvents> $target, $eventName) {
 +    $target->getEventManager()->trigger($eventName, $target);
 +}
 +?>
 +</file>
 +
 +If the object uses the trait, it will always resolve. But it also gives other classes which implement the same public API the ability to resolve the trait.
  
 ==== The Place For Current Interfaces ==== ==== The Place For Current Interfaces ====
rfc/protocol_type_hinting.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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