Programming

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Features / Spl

ArrayObject

SPL means Standard PHP Library ArrayObject allows arrays to work as objects 
  code
$array= array('a','b','c');

$obj = new ArrayObject($array);
$obj->append('d');
echo $obj->count(); // 4

$iterator = $obj->getIterator();
while($iterator->valid()) {
    echo $iterator->current(); // abcd
    $iterator->next();
}

Serializable

Interface for customized serializing 
  code        
class Obj implements Serializable 
{
    private $data;
    
    public function __construct() 
    {
        $this->data = "My private data";
    }

    public function serialize() 
    {
        return serialize($this->data);
    }

    public function unserialize($str) 
    {
        return unserialize($str);
    }
}

$obj = new Obj();

echo $str = $obj->serialize(); // s:15:"My private data";

echo $obj->unserialize($str); // My private data

ArrayAccess

Interface to provide accessing objects as arrays 
  code
class myArray implements ArrayAccess 
{
    protected $array = array();

    public function offsetExists($offset) 
    {
        return array_key_exists($this->array[$offset]);
    }

    public function offsetGet($offset) 
    {
        return $this->array[$offset];
    }
    
    public function offsetSet($offset, $value) 
    {
        if (! is_numeric($offset)) {
            throw new Exception ("Invalid Offset!");
        }
        $this->array[$offset] = $value;
    }

    public function offsetUnset($offset) 
    {
        unset($this->array[$offset]);
    }
}

$ma = new myArray();
$ma[1] = 2; // Works
$ma['a'] = 3; // Throws exception

Iterator

Interface for external objects that can be iterated themselves 
  code
class myArray implements Iterator 
{
    private $_data = array('foo', 'bar', 'baz');
    private $_current = 0;

    public function current() 
    {
        return $this->_data[$this->_current];
    }
    
    public function next() 
    {
        $this->_current += 1;
    }

    public function key() 
    {
        return $this->_current;
    }

    public function valid() 
    {
        return isset($this->_data[$this->_current]);
    }

    public function rewind() 
    {
        $this->_current = 0;
    }
}

$ma = new myArray();
echo $ma->valid(); // 1
echo $ma->current(); // foo
$ma->next();
$ma->next();
echo $ma->key(); // 2

$ma->rewind();
while($ma->valid()) {
    echo $ma->current(); // foobarbaz
    $ma->next();
}




References