===ORIGINAL===
I'm trying to implement what I think is called a "virtual method": my
abstract parent class ParentClass defines a method xxx that calls
method yyy, but yyy is defined only in ParentClass's children.
I can't get this to work (PHP5.0.4). Sample code:
=== start sample code ===
abstract class ParentClass {
// xxx just returns 5 + whatever yyy() returns
public static function xxx () {return 5 + yyy();}
// all my children must define yyy()
abstract static function yyy();
}
abstract class ChildClass extends ParentClass {
public static function yyy () {return 7;}
}
echo ChildClass::xxx();
=== end sample code ===
When I run the above, I get this error:
Fatal error: Call to undefined function yyy() in <file> on line 9
Changing the call from yyy() to self::yyy() gives a different error:
Fatal error: Cannot call abstract method ParentClass::yyy() in <file> on
line 9
How to do this correctly?
===END ORIGINAL===
The following code works..Reasons:
1. both of your classes are abstract
2. In Parent class you cannot referr to yyy() or self::yyy() cause 'self'
points to the same class and calling yyy() searches for a global yyy()
function.
abstract class ParentClass {
// xxx just returns 5 + whatever yyy() returns
public function xxx () {
return 5 + $this->yyy();
}
// all my children must define yyy()
abstract function yyy();
}
class ChildClass extends ParentClass {
public function yyy ()
{
return 7;
}
}
$obj=new ChildClass;
echo $obj->xxx();
--
Regards
Fahad Pervaiz
www.ecommerce-xperts.com
(Shopping Cart, Web Design, SEO)
