PHP abstract properties

Question

Is there any way to define abstract class properties in PHP?

abstract class Foo_Abstract {
    abstract public $tablename;
}

class Foo extends Foo_Abstract          


        

Answer 1

No, there is no way to enforce that with the compiler, you'd have to use run-time checks (say, in the constructor) for the $tablename variable, e.g.:

class Foo_Abstract {
  public final function __construct(/*whatever*/) {
    if(!isset($this->tablename))
      throw new LogicException(get_class($this) . ' must have a $tablename');
  }
}

To enforce this for all derived classes of Foo_Abstract you would have to make Foo_Abstract's constructor final, preventing overriding.

You could declare an abstract getter instead:

abstract class Foo_Abstract {
  abstract public function get_tablename();
}

class Foo extends Foo_Abstract {
  protected $tablename = 'tablename';
  public function get_tablename() {
    return $this->tablename;
  }
}