PHP Classes and Objects Late static binding
Example
In PHP 5.3+ and above you can utilize late static binding to control which class a static property or method is called from. It was added to overcome the problem inherent with the self:: scope resolutor. Take the following code
class Horse {
public static function whatToSay() {
echo 'Neigh!';
}
public static function speak() {
self::whatToSay();
}
}
class MrEd extends Horse {
public static function whatToSay() {
echo 'Hello Wilbur!';
}
}
You would expect that the MrEd class will override the parent whatToSay() function. But when we run this we get something unexpected
Horse::speak(); // Neigh!
MrEd::speak(); // Neigh!
The problem is that self::whatToSay(); can only refer to the Horse class, meaning it doesn't obey MrEd. If we switch to the static:: scope resolutor, we don't have this problem. This newer method tells the class to obey the instance calling it. Thus we get the inheritance we're expecting
class Horse {
public static function whatToSay() {
echo 'Neigh!';
}
public static function speak() {
static::whatToSay(); // Late Static Binding
}
}
Horse::speak(); // Neigh!
MrEd::speak(); // Hello Wilbur!
