Example usage via calls outside of the class and within an object:

<?php
/**
 * @author Jonathon Hibbard
 */
class foo {
  # used to verify we're actually setting something..
  private static $value = '';

  /**
   * Simple setter for the static method setValue...
   */
  public static function set($method_identifier, $value_to_pass = '') {
    # make sure we have the right method format...
    # another semi-useful example is like this (useful for REST-like requests...): str_replace(" ", "", ucwords(str_replace("_", " ",  $method_identifier)));
    $static_method = 'set' . ucfirst(strtolower(trim($method_identifier)));

    if(method_exists(__CLASS__, $static_method)) {
      //Note:  this will not work and will throw PHP Parse error:  syntax error, unexpected '::'
      //__CLASS__::$static_method($value_to_pass);

      foo::$static_method($value_to_pass);

      echo "\tCalling forward_static_call with pure string and value param:\n";
      forward_static_call(__CLASS__ . "::" . $static_method, $value_to_pass);

      echo "\tCalling forward_static_call with class, method array and value param:\n";
      forward_static_call(array(__CLASS__, $static_method), $value_to_pass);
    }
  }

  /**
   * Set self::$value to something?
   */
  public static function setValue($value_recieved = '') {
    echo "\t\tsetValue called with param of " . var_export($value_recieved, true) . "!\n";

    echo "\t\tSetting Private 'value'...\n";

    self::$value = $value_recieved;

    echo "\t\tChecking the Private 'value':\n";
    if(!empty(self::$value)) {
      echo "\t\t\tPrivate 'value' was set to '" . self::$value . "' as expected!\n";
    } else {
      echo "\t\t\tPrivate 'value' was not set!\n";
    }

    # Reset...
    self::$value = '';
  }

  /**
   * Create an object and test calling the static method from within this realm...
   */
  public function __construct() {
    echo "\tCalling from within constructor..\n";
    foo::set('value','Something else from within the instance!');
  }
}

echo "\n============ Calling by static method first ============\n";
foo::set('value','Something from outside of the foo class!');

echo "\n============ Calling by static method without a value next ============\n";
foo::set('value');

echo "\n============ Calling by createing an instance next ============\n";
new foo();
?>