get filename of extended class

Question

Let\'s say I have two files, each one has a class. How can I get the filename where the child class is, within the parent class?

File 2 (child class):

Answer 1

You can cheat and use debug_backtrace:

class A {
  final protected function __construct() {
    $stacktrace = @debug_backtrace(false);
    $filename = $stacktrace[0]['file'];
  }
}

Answer 2

Not really sure what purpose it serves, but here you go:

class A{

  final protected function __construct(){
    $obj = new ReflectionClass($this);
    $filename = $obj->getFileName();
  }

}