Getting child class info from extends construction

I'm not quite sure how to formulate my question, so sorry in advance for this uninformative title.

So here is the problem. I have a couple of files in the same directory, each of them is a class holder. When i inherit one of the classes i need to know in which fi开发者_运维百科le (or more like the folder) i do it.

I don't really like the solution i came to, but still to demonstrate what exactly i mean.

foo.php

class Foo {
}

bar.php

include_once 'bootstrap.php' ;

class Bar extends Foo {
}

$bar = new Bar() ;

bootstrap.php

function __autoload( $class ) {
    $trace = debug_backtrace() ;
    // Here i've got the directory i need:
    $folder = dirname( $trace[ 0 ][ 'file' ] ) ; 
}

Is there any other (proper) way to get folder name, cause it debug_backtrace is not actually meant for this kind of operations. And not good from the performance point of view either.

Limitation: should work for php 5.2.12

$folder = dirname(__FILE__) doesn't do the job?

The magic constant __FILE__ reports the file name (with path) of the file it is called in (see the PHP docs):

__FILE__ : The full path and filename of the file. If used inside an include, the name of the included file is returned. Since PHP 4.0.2, __FILE__ always contains an absolute path with symlinks resolved whereas in older versions it contained relative path under some circumstances.

That means you can create a method that returns the classes file name.

For example, in 'test-folder/Foo.php':

class Foo {

   function getFile() {
      return __FILE__;
   }

}

And in 'Bar.php`:

include 'test-folder/Foo.php';

class Bar extends Foo {

   function getParentFile() {
      return parent::getFile();
   }

}

$bar = new Bar();

echo dirname($bar ->getParentFile());
// result: C:\wamp\www\test-folder

EDIT: Ok, so if you want to find out where the parent class is before creating it, this should work (using Reflection):

$reflectedBar = new ReflectionClass('Bar');
$reflectedBarParent = $reflectedBar->getParentClass();
$filename = $reflectedBarParent->getFileName();