PHP OOP - Pass data between classes through the calling class? - php

Question

I'm struggling to find a correct approach to pass data between classes, which do not directly call each other, and are only related through a parent class (which I now use, but I consider it a dirty workaround rather than anything near a solution).
I have 3 classes both able to read input and write output, and based on configuration I set one to read, another one to write. It may even be the same class, they all share a parent class, but they are always two separate instances called from a controller class.
Currently I use this sort of functionality:
class daddy {
public static $data;
}
class son extends daddy {
public function setData() {
parent::$data = "candy";
}
}
class daughter extends daddy {
public function getData() {
echo parent::$data;
}
}
while($processALineFromConfig)
$son = new son;
$son->setData();
$daughter = new daughter;
$daughter->getData();
daddy::$data = null; //reset the data, in the actual code $daughter does that in parent::
}
Instantination of these classes runs in a loop, therefore I always need to reset the data after $daughter receives them, 'cos otherwise it would stay there for another pass through the loop.
I'm absolutely sure it's not how class inheritance is supposed to be used, however I'm struggling to find a real solution. It only makes sense the data should be stored in the controller which calls these classes, not the parent, but I already use return values in the setter and getter functions, and I am not passing a variable by reference to store it there to these functions 'cos I have optional parameters there and I'm trying to keep the code clean.
What would be the correct approach to pass data through the controller then?
Thanks!

Answer 1

The best option would be for two object share some other, third object. This would be the class for "third object" which will ensure the exchage:
class Messenger
{
private $data;
public function store($value)
{
$this->data = $value;
}
public function fetch()
{
return $this->data;
}
}
Then a class for both instance, that will need to share some state:
class FooBar
{
private $messenger;
private $name = 'Nobody';
public function __construct($messenger, $name)
{
$this->messenger = messenger;
$this->name = $name;
}
public function setSharedParam($value)
{
$this->messenger->store($value);
}
public function getSharedParameter()
{
return $this->name . ': ' . $this->messenger->fetch();
}
}
You utilize the classes like this:
$conduit = new Messenger;
$john = new FooBar($conduit, 'Crichton');
$dominar = new FooBar($conduit, 'Rygel');
$dominar->setSharedParameter('crackers');
echo $john->getSharedParameter();
// Crichton: crackers
Basically, they both are accessing the same object. This also can be further expanded by making both instance to observe the instance of Messenger.