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Simple Dependency Resolver in PHP. Dependency Autowiring.
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<?php | |
/* | |
* USAGE: | |
* | |
* // this is where I define all my dependencies in case if they are not directly instantiable (resolvable) | |
* $deps = array( | |
* 'DependentClass' => array( | |
* 'depclass' => 'DependencyClass' | |
* ) | |
* ); | |
* ObjectManager::getInstance()->setDependencies($deps); | |
* | |
* class DependentClass { | |
* private $depclass; | |
* private $dep2; | |
* function __constructor(DependencyClassInterface $depclass, DirectlyResolvableClass $dep2) { | |
* $this->dep2 = $dep2; | |
* $this->depclass = $depclass; | |
* } | |
* function doSomething() {} | |
* } | |
* | |
* ObjectManager::getInstance() | |
* ->get('DependentClass') | |
* ->doSomething(); | |
* | |
*/ | |
class ObjectManager | |
{ | |
protected $dependencies; | |
protected static $omInstance; | |
public static function getInstance() | |
{ | |
if (!self::$omInstance) { | |
self::$omInstance = new ObjectManager(); | |
} | |
return self::$omInstance; | |
} | |
public function setDependencies(array $dependencies) | |
{ | |
$this->dependencies = $dependencies; | |
} | |
public function getDependencies() | |
{ | |
return $this->dependencies; | |
} | |
public function get($class) | |
{ | |
$finalizedParams = array(); | |
$deps = array(); | |
// check if deps are defined | |
if (array_key_exists($class, $this->dependencies)) { | |
$deps = $this->dependencies[$class]; | |
} | |
$reflector = new ReflectionClass($class); | |
if (!$reflector->isInstantiable()) { | |
throw new Exception("Class {$class} is not instantiable"); | |
} | |
$constructor = $reflector->getConstructor(); | |
if ($constructor == null) { | |
return $reflector->newInstance(); | |
} | |
$parameters = $constructor->getParameters(); | |
foreach ($parameters as $key => $parameter) { | |
$parameterType = $this->getParameterType($parameter); | |
$parameterName = $parameter->getName(); | |
if ($parameterType == null) { | |
if ($parameter->isDefaultValueAvailable()) { | |
$finalizedParams[$key] = $parameter->getDefaultValue(); | |
} else { | |
throw new Exception(" | |
Failed resolving argument (dependency) \"$parameterName\" for class $class. | |
Not directly instantiatable. | |
No default value specified."); | |
} | |
continue; | |
} | |
$classReflection = new ReflectionClass($parameterType); | |
// if dep is directly instantiable; save and continue | |
if ($classReflection->isInstantiable()) { | |
$finalizedParams[$key] = $classReflection->newInstance(); | |
continue; | |
} | |
// if defined in di.php | |
if (array_key_exists($parameterName, $deps)) { | |
$argName = $deps[$parameterName]; | |
$finalizedParams[$key] = ObjectManager::getInstance()->get($argName); | |
continue; | |
} | |
} | |
return $reflector->newInstanceArgs($finalizedParams); | |
} | |
protected function getParameterType(ReflectionParameter $parameter) | |
{ | |
$export = ReflectionParameter::export( | |
array( | |
$parameter->getDeclaringClass()->name, | |
$parameter->getDeclaringFunction()->name, | |
), | |
$parameter->name, | |
true | |
); | |
return preg_match('/[>] ([A-z]+) /', $export, $matches) | |
? $matches[1] : null; | |
} | |
} |
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