Since it is possible methods will have the same name or signature accross multiple classes, the way to specify which class the method you are calling belongs to is:
ClassName::method_name();
Variations of this are:
- parent::method_name(); // Calling the class parent method
- self::method_name(); // Same as $this->method_name();
In PHP4, you could call any method using this syntaxis, in PHP5, since now we have visibility attributes, you can only call static functions with it.
So the syntaxis above is used to call overriden parent methods, instead of the current class ones, for instance: $base = parent::getSummaryLine(); to call the parent getSummaryLine() method, not the overriden version of it in this object.