php访问子类的父对象（无继承）

Question

I have a core class as a collector and two subclasses stored in public variables in this core class:

class Core
{
  public $cache;
  public $html;

  public function __construct()
  {
    $cache = new Cache();
    $html  = new Html();
  }
}

class Cache
{
  public function __construct()
  {
  }

  public function store($value)
  {
    // do something
  }
}

class Html
{
  public $foo;

  public function __construct()
  {
    $foo = "bar";
    global $core;
    $core->cache->store($foo);
  }

}

QUESTION: I would like to get rid of the line "global $core" and do something like: $this->parent->cache->store($foo) $cache should be connected to $core in some way because it is a public member of $core

I know that $html is a subclass stored as a variable and not an inheritance. Any ideas?

Second question: Can I leave out the empty constructor in the Cache-Class?

Answer 1

Your object can't access caller class methods, because he do not know anything about it's caller.

You can try to pass parent when creating new object

class Core {
   public $cache;
   public $html;

   public function __construct() {
       $this->cache = new Cache($this);
       $this->html = new Html($this);
   }
}

class Html {
    public $parent;

    public function __construct($parent) {
        $this->parent = $parent;

        if (!empty($this->parent->cache)) {
            $this->parent->cache->store();
        }
    }
}

---

Can I leave out the empty constructor - yes, you even do not have to declare __construct method at all, as all classes has it's default constructor/destructor.