abstract classes and inheritance in php5

abstract class Foo {
final function __construct() {

}
abstract function init();
}
class Parser extends Foo {
function init() {

}
}
class CssParser extends Parser {

}
/*
in a code like the above, how can you force all the inherited classes to
implement a method like init() ?
*/

Ollie wrote:
> in a code like the above, how can you force all the inherited classes
> to implement a method like init() ?
>

Not possible, because only the class that extends the abstract class is
forced to implement the method.

Other classes just inherit the method.


JW

Janwillem Borleffs wrote:
> Not possible, because only the class that extends the abstract class
> is forced to implement the method.
>
> Other classes just inherit the method.
>

However, there is a way using the Reflection API:

abstract class Foo {
final function __construct() {
$rm = new ReflectionMethod($this, 'init');
if (get_class($this) != $rm->getDeclaringClass()->getName()) {
throw new Exception("init() method must be implemented");
}
}
abstract function init();
}

But be aware that using the Reflection API in production applications can
have a negative impact on performance.


JW