How to get the path of a derived class from an inherited method?

Question

How to get the path of the current class, from an inherited method?

I have the following:

<?php // file: /parentDir/class.php
   class Parent  {
      protected function getDir() {
         return dirname(__FILE__);
      }
   }
?>

and

<?php // file: /childDir/class.php
   class Child extends Parent {
      public function __construct() {
         echo $this->getDir(); 
      }
   }
   $tmp = new Child(); // output: '/parentDir'
?>

The __FILE__ constant always points to the source-file of the file it is in, regardless of inheritance.
I would like to get the name of the path for the derived class.

Is there any elegant way of doing this?

I could do something along the lines of $this->getDir(__FILE__); but that would mean that I have to repeat myself quite often. I'm looking for a method that puts all the logic in the parent class, if possible.

Update:
Accepted solution (by Palantir):

<?php // file: /parentDir/class.php
   class Parent  {
      protected function getDir() {
         $reflector = new ReflectionClass(get_class($this));
         return dirname($reflector->getFileName());
      }
   }
?>

Solution 1

Using ReflectionClass::getFileName with this will get you the dirname the class Child is defined on.

$reflector = new ReflectionClass("Child");
$fn = $reflector->getFileName();
return dirname($fn);

You can get the class name of an object with get_class() :)

Solution 2

Yes. Building on Palantir's answer:

   class Parent  {
      protected function getDir() {
         $rc = new ReflectionClass(get_class($this));
         return dirname($rc->getFileName());
      }
   }

Solution 3

Don't forget, since 5.5 you can use class keyword for the class name resolution, which would be a lot faster than calling get_class($this). The accepted solution would look like this:

protected function getDir() {
    return dirname((new ReflectionClass(static::class))->getFileName());
}

Solution 4

If you are using Composer for autoloading you can retrieve the directory without reflection.

$autoloader = require 'project_root/vendor/autoload.php';
// Use get_called_class() for PHP 5.3 and 5.4
$file = $autoloader->findFile(static::class);
$directory = dirname($file);

Solution 5

<?php // file: /parentDir/class.php
   class Parent  {
      const FILE = __FILE__;
      protected function getDir() {
         return dirname($this::FILE);
      }
   }
?>


<?php // file: /childDir/class.php
   class Child extends Parent {
      const FILE = __FILE__;
      public function __construct() {
         echo $this->getDir(); 
      }
   }
   $tmp = new Child(); // output: '/childDir'
?>

Please not that if you need to get the dir, directly use __DIR__.

View more solutions

Comments

[Dan Johnson]

Mate, I have spent about 4 hours today searching for a way to do this without using Reflection!! Thanks!

[coccoinomane]

Thanks! If you are using namespaces, make sure to change new ReflectionClass(...) with new \ReflectionClass(...).