跨多个类文件访问PHP静态变量

I have a PHP class file A with a static variable, I have one class file B that uses that class A and instantiates its static variable. i wish to access Class A's ststic varibale from another class C in another file. How do i do this. I tried this.I know of the singleton structure but am not sure it applies to this. take a look below of what am trying to achieve. Please not i do not wish to use sessions.

classA.php

  <?php
   Class A{
  public static $foo = array ();
 public static function doSomething(){
   //... Do some process and instantiate static vairable $face
   self::$foo = outputofsomeprocess();
 }
}
?>

classB.php

<?php
require_once "classA.php";
class B{
public function dosomethingelse(){
    A::doSomething();
}
}
?>

classC.php

<?php
require_once "classA.php";
 class C{
    public function dosomethingelse(){
    echo A::$foo[0];
   }
  }
?>

I get null from the echo in class C

Coming from a C# background, it's a bit different but that should do the trick.

class A1 {

    public static $foo = array();

}


<?php
require_once 'classA.php';

class B2 {

    public static function doSomethings() {

       var_dump(A1::$foo);
    }
}

B2::doSomethings();