Is it possible to either
extend an extension of a class e.g.:
class a {
}
class b extends a {
}
class c extends b {
}
EDIT:
[or some other way that class c can use functions only defined in b but not in a.]
Well I just notice that my question was kinda messed up. c should be able to use all functions, so of course those of a aswell.
I'll just accept the answer solving my non-existing problem, in case someone searches for this.
Since PHP 5.4 you can use traits which may be of help to you. You can define two traits, one with the functions that class a has and one containing functions that class b has, but not class a.
So:
trait TraitA {
function a1() { }
function a2() { }
}
trait TraitB {
function b1() { }
function b2() { }
}
Then you can define a class a that uses only TraitA, a class b that uses both traits, and a class c that uses only TraitB:
class a {
use TraitA
// contains a1 and a2
}
class b {
use TraitA, TraitB
// contains a1, a2, b1 and b2
}
class a {
use TraitB
// contains b1 and b2
}
More on traits: http://php.net/manual/en/language.oop5.traits.php Keep in mind that you have to pay attention to your function names between different traits. You can't have the same functionnames in both traits or you'll get collisions.
This isn't possible. By definition class B is an "extension" of class A. This means that class if class a has the method method_in_class_a() then class B will have method_in_class_a() as a BASE before you even configure the class.
All you need to do is to do it the other way around:
class b { ... }
class a extends b { /* has methods from b and a */ }
class c extends b { /* can only use methods from b */ }
I'm not sure why you need to do this but...
Unless methods and properties are defined as private methods, all extending classes will have access to them and can be extended, unless the parent method is declared as final.
However, since PHP5.4, you can use Traits.
<?php
trait BOnly
{
function getReturnType() { /* 1 */ }
function getReturnDescription() { /* 2 */ }
}
class A
{
}
class B extends A
{
use BOnly;
}
class C extends B
{
}
