README

A contract for ioc-containers

Do not use this library as long it is not 1.0.

Abstract

This project provides a documentation for the api and the behavior of three different concerns:

• InstanceContainer - a container that returns instances associated with keys.
• ObjectFactory - an abstract factory to create new object-instances from. E.g. used in factories to create new entities.
• MethodInvoker - invoke a method, function or closure. E.g. used in dispatchers to start a subprogram.

Motivation

Lets say you wan't to build a rule-based service-dispatcher (or an http-router like silex), that invoke registered closures only if a certain condition is met:

$serviceDispatcher = new ServiceDispatcher();
$serviceDispatcher->register('service-name', 3600 /* timeout sek. */, function () {
	/* do something every hour */
});
$serviceDispatcher->run();

It would be fun, if I already had the domain-objects I need to work with. This would look like this:

$serviceDispatcher = new ServiceDispatcher();
$serviceDispatcher->register('service-name', 3600 /* timeout sek. */, function (BusinessObject $businessObject) {
	/* do something every hour */
	$businessObject->doSomething();
});
$serviceDispatcher->run();

$serviceDispatcher should not be aware of a BusinessObject directly. But the ServiceDispatcher may know of an generic way to call a callable (like a closure) and resolve those parameters by a component outside of ServiceDispatcher's scope. How this is archived is not a concern of the ServiceDispatcher. It just happens somehow.

The goal could be archived with an Dependency-Injection-Container. There are different ioc-containers out there with quite different interfaces (my current favorite is PHP-DI). So we need a common interface to pass an instance around which is aware of how to instantiate our domain-objects so that we could directly use them:

$container = new Container(require 'config/di-cfg.php');
$serviceDispatcher = new ServiceDispatcher($container);
$serviceDispatcher->register('service-name', 3600 /* timeout sek. */, function (BusinessObject $businessObject) {
	/* do something every hour */
	$businessObject->doSomething();
});
$serviceDispatcher->run();

Now the run-method in the ServiceDispatcher-implementation could simply look like this:

use Ioc\MethodInvoker;

class ServiceDispatcher {
	/** @var MethodInvoker */
	private $methodInvoker;

	/* ... */

	/** @param MethodInvoker $methodInvoker */
	public function __construct(MethodInvoker $methodInvoker) {
		$this->methodInvoker = $methodInvoker;
	}

	/* ... */

	public function run() {
		foreach($this->registry as $serviceName => $service) {
			if($service['lockUntil'] > time()) {
				continue;
			}
			try {
				$this->methodInvoker->invoke($service['fn'], array('serviceName' => $serviceName));
			} finally {
				$service['lockUntil'] = time() + $service['timeout'];
			}
		}
	}
}

InstanceContainer

A InstanceContainer is mostly useful when in subjection to a di-container only a single instance of an object should be used. This is slightly different to the use of a singleton-pattern since you can have multiple di-containers with different configurations that may inject different implementations for the provided interfaces. For implementation details, look at the phpdoc-blocks.

ObjectFactory

A ObjectFactory is mostly useful in common factories to create entities. For implementation details, look at the phpdoc-blocks.

MethodInvoker

Invokes a callable method, function or closure and resolve the required parameters automatically of not already provided. For implementation details, look at the phpdoc-blocks.