[PHP]How to check if a class inherits another class without instantiating it?

Question

I have some class name. How to check if a class inherits another class without instantiating it?

 if (!class_exists($controller)) //AND I have check type
            


        

Answer 1

I know this is an old question, though it ranks high on Google right now and brought me here while looking for an alternative to reflection. After not finding any, I decided to post a working example for all here.

You can do this by using reflection. Try not to rely on reflection too much since it can be resource-intensive.

class TestA {}
class TestB extends TestA {}
class TestC extends TestA {}

$reflector = new ReflectionClass('TestA');
$result    = $reflector->isSubclassOf('TestA');
var_dump($result); // false

$reflector = new ReflectionClass('TestB');
$result    = $reflector->isSubclassOf('TestA');
var_dump($result); // true

$reflector = new ReflectionClass('TestC');
$result    = $reflector->isSubclassOf('TestA');
var_dump($result); // false

For more info on class reflection, see http://www.php.net/manual/en/class.reflectionclass.php

For more info on reflection in general, see http://php.net/reflection