Extending interfaces
21. Januar 2009
comments feedWhat many people don't know is that you cannot only extend classes in PHP but also interfaces:
interface First_Interface
{
public function show();
}
interface Second_Interface extends First_Interface
{
public function update();
}
class Product implements Second_Interface
{
public function show() {}
public function update() {}
}
You have to remember though that extending is not possible when you have the same function in both interfaces:
interface Second_Interface extends First_Interface
{
public function show();
public function update();
}
This will lead to a PHP Fatal Error:
PHP Fatal error: Can't inherit abstract function First_Interface::show() (previously declared abstract in Second_Interface) in /tmp/interfaces.php on line 8
Fatal error: Can't inherit abstract function First_Interface::show() (previously declared abstract in Second_Interface) in /tmp/interfaces.php on line 8
Note: This possibility is also described in the PHP documentation for interfaces (Example #3)
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