ConstructorReflection.php

<?php

interface ITest {

}

 class TestClass1 {
	
 }
 
 class TestClass2 {
	public function __construct(TestClass1 $param1, DateTime $param2, $param3) {
	
	}
 }
 
 class TestClass3 extends TestClass2 {
 
 }
 
  class TestClass4 {
	public function __construct(ITest $test) {
	
	}
 }
 
 function getConstructorParamClasses($className) {
	$classReflection = new ReflectionClass($className);
	$constructorReflection = $classReflection->getConstructor();
	if ($constructorReflection === NULL) {
		return array();
	}
	$classes = array();
	foreach ($constructorReflection->getParameters() as $paramReflection) {
		$paramClass = $paramReflection->getClass();
		$classes[] = $paramClass ? $paramClass->getName() : NULL;
	}
	return $classes;
 }
 
 echo '<pre>';
 var_dump(getConstructorParamClasses("TestClass1"));
 var_dump(getConstructorParamClasses("TestClass2"));
 var_dump(getConstructorParamClasses("TestClass3"));
 var_dump(getConstructorParamClasses("TestClass4"));