If I have several classes with functions that I need but want to store separately for organisation, can I extend a class to have both?
i.e. class a extends b extends c
edit: I know how to extend classes one at a time, but I'm looking for a method to instantly extend a class using multiple base classes - AFAIK you can't do this in PHP but there should be ways around it without resorting to class c extends b
, class b extends a
As of PHP 5.4.0 there are "Traits" - you can use more traits in one class, so the final deciding point would be whether you want really an inheritance or you just need some "feature"(trait). Trait is, vaguely said, an already implemented interface that is meant to be just use
d.
No you can't, respectively, not really, as manual of extends
keyword says:
An extended class is always dependent on a single base class, that is, multiple inheritance is not supported.
However as @adam suggested correctly this does NOT forbids you to use multiple hierarchal inheritance.
You CAN extend one class, with another and another with another and so on...
So pretty simple example on this would be:
class firstInheritance{}
class secondInheritance extends firstInheritance{}
class someFinalClass extends secondInheritance{}
//...and so on...
As you might have noticed, you can only do multiple(2+) intehritance by hierarchy if you have control over all classes included in the process - that means, you can't apply this solution e.g. with built-in classes or with classes you simply can't edit - if you want to do that, you are left with the @Franck solution - child instances.
...And finally example with some output:
class A{
function a_hi(){
echo "I am a of A".PHP_EOL."<br>".PHP_EOL;
}
}
class B extends A{
function b_hi(){
echo "I am b of B".PHP_EOL."<br>".PHP_EOL;
}
}
class C extends B{
function c_hi(){
echo "I am c of C".PHP_EOL."<br>".PHP_EOL;
}
}
$myTestInstance = new C();
$myTestInstance->a_hi();
$myTestInstance->b_hi();
$myTestInstance->c_hi();
Which outputs
I am a of A
I am b of B
I am c of C