PHP扩展了一个从另一个类调用的类方法，该类方法对其进行扩展并使用parent :: method调用该方法

Question

I am trying to extend a class and override one of its methods. lets call that class A. My class, class B, is overiding a protected method. Class C extends class A and Class D extends class C. Inside of Class D, the method I am trying to overwrite is also extended here and that calls parent::mymethodimoverriding. That method does not exist in class C so it goes to it in class A. That is the method I am overiding in class B and obviously you can't extend A with B and have those changes show up in D since it does not fall in line with the class hierarchy. I might be wrong, so correct me please.

so if my class b is called and ran then class D gets called it runs the method in A and overwrites what I had set. I am thinking there must be a way to get this to work, I am just missing something.

Here is an example, as you can see in class A there is a call to setTitle and it is set to "Example" In my class I set it to "NewExample". My class is getting called before class D so when class D is called it goes back to the parent and sets the title back to "Example". What I would like to happen is class B runs and sets it to do what I need it to then class D run and instead of it hitting the class I am extending for it to hit my class instead. the thing is I don't think I can make class D extend my class. so now it is hitting the class I am extending

class A{
  protected function _thefunction(){
    setTitle("Example");
  }
}

class B extends A{
  protected function _thefunction(){
    My new code here
    setTitle("NewExample");
  }
}

class C extends A{
  nothing that matters in here for what I am doing
}

class D extends C{
  protected function _thefunction(){
    parent::_thefunction();
    additional code here
  }
}

I tried doing

class D extends C{
  protected function _thefunction(){
    B::_thefunction();
    additional code here
  }
}

and I got errors about it not being a static method

Answer 1

From what I can understand _thefunction() does something to another object($headBlock?). Your class (B) changes something in that object, then class D goes and changes it back to something else. Only way to fix this is to somehow disable D's intereference or have class B's method run after it.

You could use inheritance by having C inherit B instead of A, although I don't know what side-effects these might have to the structure of your program.

Edit: Seeing as this is Magento we are talking about, maybe you should ask specifically about Magento either in SO or the Magento forums. There's very little you can't override in it; maybe you've taken a wrong turn somewhere in your approach?

Answer 2

That is the method I am overiding in class B and obviously you can't extend A with B and have those changes show up in D since it does not fall in line with the class hierarchy. I might be wrong, so correct me please.

I'm afraid you're right here. If you don't rework the whole concept there's not much you can do.

I tried to disable the interference by having it call myclass::thefunction but of course I got an error saying something about it not being a static method.

Are you able to modify class D? I don't understand this part. If so, you wouldn't be asking this question in the first place, I presume.

Maybe some specifics about Magento could help? There's probably some other way to achieve the desired outcome.

Answer 3

What you are trying to do probably can't be done for at least of two reasons:

1. Method _thefunction() is protected in B so it is accessible only for B and its descendants.
2. You can't call method of object B for object of class D because D is not neither B nor descendant of B.

Answer 4

You are trying to call B::_theFunciton() but the method in B is protected (meaning that all access to that method is reserved for its own class or any subclasses, which D is not, the class hierarchy for D is... A->C->D, no B in there.)

The function is also not static, so you cant reference it like B::blah()

If you really want this then you could define _theFunction as public static, however if you really think that is an object related method then the only good practice way is to be a subclass from it.