6CC001 Workshop - week 03

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Static classes - An example

class Preferences
{
  private static $values = array();
  
  static function set($key, $val)
  {
    self::$values[$key] = $val;
  }
  
  static function get($key)
  {
    return self::$values[$key];
  }
}

Preferences::set("db_server", "mi-linux");

$db_server = Preferences::get("db_server");
echo $db_server;

Abstract classes - an example

An abstract class cannot be instantiated, i.e. you cannot use the “new” operator to create objects.

An abstract class defines (and optionally partially implements) the interface for any class that might extend it (via inheritance).

abstract class Shape
{
  protected $height;
  protected $width;
  
  public function __construct($height, $width)
  {
    $this->height = $height;
    $this->width = $width;
  }
  
  abstract public function CalculateSurface();
}