PHP OOP: Parenting objects/functions?

Question

Hi everyone,

How is parenting functions in PHP done properly according to the following example? Can I make sure that my array isn't overwritten and the previous values inside array lost, on each addArray call?

function arraybase() {
    $this->array = new ArrayObject();

    return $this;
}

function addArray($value) {
     parent::$this->arraybase();

    $this->array->append($value);
    return $this;

}


$this->addArray('1')->addArray('2')->addArray('3'); 

// outputs:
Array
(
    [0] => 3
)

Thanks a lot!

Answer 1

In function addArray you keep recreating the array with the line:

parent::$this->arraybase();

Remove this line and call arraybase when you want to create it.

Answer 2

Well, first off, you don't need to parent::$this->arraybase(). Just do $this->arraybase(). In fact, I'm not even sure your way is even valid syntax. But I digress.

As for your specific problem, you can either:

1. Add a constructor (and remove the ->arraybase() call from addArray()):

   public function __construct() {
       $this->array = new ArrayObject();
   }
   

2. Add an if check around the call to ->arraybase():

   public function addArray($value) {
       if (!isset($this->array) || !is_object($this->array)) {
           $this->arraybase();
       }
       ...
   }
   

Personally, I'd do #1. It's going to be more reliable, faster, and more in keeping with OOP paradigms.

EDIT: Adding Constructor Info

So, if your base class has this constructor:

public function __construct($some, $vars) {
    ......
}

You would do this in your extending class:

public function __construct($some, $vars) {
    parent::__construct($some, $vars);
    $this->array = new ArrayObject();
}

NOTE: Don't call parent::__construct() unless one of the parents has a __construct method...

Answer 3

Why do you want to set a wrapper around ArrayObject? If it's for adding the possibility of chaining method calls, then you'd better extend ArrayObject:

<?php
class MyArrayObject extends ArrayObject {

    public function append($value)
    {
        parent::append($value);
        return $this;
    }
}

$ao = new MyArrayObject();
$ao->append('a')->append('b')->append('c');
var_dump($ao->getArrayCopy());
/*
array(3) {
  [0]=>
  string(1) "a"
  [1]=>
  string(1) "b"
  [2]=>
  string(1) "c"
}
*/