PHP 5.3 Lightweight IOC container

ioc.php

<?php

/*
 * Lightweight IOC container
 */

class IOC {
	
	// if a hinted class name is matched here
	// use the associated value as the new class
	private $constraints = array();
	
	// object cache
	private $cache;
	private $objectCache = array();
	
	
	
	public function __construct($cache = false) {
		$this->cache = $cache;
	}
	
	public function forClass($originalHinted, $newClass) {
		if (!array_key_exists($originalHinted, $this->constraints)) {
			$this->constraints[$originalHinted] = $newClass;
		}
	}
	
	public function make($object) {
		
		// parameters for the construct of object	
		$objectParameters = array();
		
		// all the arguments passed to make
		// can be of any type
		$args = func_get_args();
		
		// skip the object name for the other types of parameters
		array_shift($args);	
		
		if (is_string($object) && class_exists($object)) {
			// defining class for the object we try to make
			$ref = new ReflectionClass($object);
			
			// object constructor
			$constructor = $ref->getConstructor();
			
			if ($constructor) {
			
				// constructor parameters
				$constructorParameters = $constructor->getParameters();
		
				$otherTypeParameterCounter = 0; // incremented only when the type of the arg is not a class
				foreach ($constructorParameters as $parameter) {
	
					// the parameter should be an instance of the hinted class
					$hintedClass = $parameter->getClass();
					if ($hintedClass != NULL) {
						$hintedClassName = $hintedClass->getName();
						
						// overridden hinted class
						if (array_key_exists($hintedClassName, $this->constraints)) {
							$hintedClassName = $this->constraints[$hintedClassName];
						}
						
						// instantiate the class and add it to the
						// parameters list
						if (class_exists($hintedClassName)) {
							// the hinted class could have hinted class parameters and other types as well
							$objectParameters[] = $this->make($hintedClassName);
						}
						
					} else {
						// other type of parameter
						// found in the args array
						// these parameters are passed to the make function after
						// the object to create
						$objectParameters[] = $args[$otherTypeParameterCounter];					
						$otherTypeParameterCounter++;
					}
					
				}
				
			}
			
			
			if (empty($objectParameters)) {
				if ($this->cache) {
					$objectIdentifier = $ref->name;		
					if (array_key_exists($objectIdentifier, $this->objectCache)) {
						return $this->objectCache[$objectIdentifier];
					} else {
						$o = new $object;
						$this->objectCache[$objectIdentifier] = $o;
						return $o;
					}	
				} else {
					return new $object;
				}
				
				
			} else {
				
				if ($this->cache) {
					$objectIdentifier = $ref->name . md5(serialize($objectParameters));
					if (array_key_exists($objectIdentifier, $this->objectCache)) {
						return $this->objectCache[$objectIdentifier];
					} else {
						$o = $ref->newInstanceArgs($objectParameters);
						$this->objectCache[$objectIdentifier] = $o;
						return $o;
					}	
				} else {
					return $ref->newInstanceArgs($objectParameters);
				}
					
			}
			
		} else {
			die("Invalid use of IOC, $object is not a class.");
		}
		
	}
	
}

output.txt

object(SteelDoor)[12]
  private 'material' => 
    object(Steel)[13]
      private 'materialName' (Material) => string 'steel' (length=5)
  private 'strength' => int 5

object(WoodWindow)[14]
  private 'material' => 
    object(Wood)[15]
      private 'materialName' (Material) => string 'wood' (length=4)

object(ReinforcedSteelDoor)[17]
  private 'material' (SteelDoor) => 
    object(Steel)[18]
      private 'materialName' (Material) => string 'steel' (length=5)
  private 'strength' (SteelDoor) => int 10

object(WoodWindow)[19]
  private 'material' => 
    object(Wood)[20]
      private 'materialName' (Material) => string 'wood' (length=4)

usage_example.php

<?php
require_once 'ioc.class.php';

class Material {

	private $materialName = null;

	public function __construct() {
		
	}
	
	public function setMaterialName($name) {
		$this->materialName = $name;
	}
	
	public function getMaterialName() {
		return $this->materialName;
	}
	
}

class Wood extends Material {

	public function __construct() {
		parent::__construct();
		$this->setMaterialName("wood");
	}
	
}

class Steel extends Material {

	public function __construct() {
		parent::__construct();
		$this->setMaterialName("steel");
	}
	
}



class WoodWindow {
	
	private $material;
	
	public function __construct(Wood $material) {
		$this->material = $material;
	}
	
	public function getWindowMaterial() {
		return $this->material->getMaterialName();
	}
	
}

class SteelDoor {
	
	private $material;
	private $strength = 5;
	
	public function __construct(Steel $material) {
		$this->material = $material;
	}
	
	public function getDoorMaterial() {
		return $this->material->getMaterialName();
	}
	
	public function setStrength($strength) {
		$this->strength = $strength;
	}
	
}

class ReinforcedSteelDoor extends SteelDoor {
	
	public function __construct(Steel $material) {
		parent::__construct($material);
		$this->setStrength(10);
	}
	
}

class House {
	
	private $door;
	private $window;
	
	public function __construct(SteelDoor $door, WoodWindow $window) {
		$this->door = $door;
		$this->window = $window;
	}
	
	public function describe() {
		var_dump($this->door);
		var_dump($this->window);
	}
	
}


$ioc = new IOC(); // pass true to the constructor for object caching
$house = $ioc->make("House");
$house->describe();

// how about a better door
// just override the used class for the steel door
$ioc->forClass("SteelDoor", "ReinforcedSteelDoor");
$house = $ioc->make("House");
$house->describe();