Lazy loading with attributes over php

class BaseClass
{
protected function __get_xml()
{
$str = ''; for ($n = 0; $n < 10; $n++) $str .= 'XML';
return $str;
}
}


class LazyClassAtribute extends BaseClass
{
public function __get( $name )
{
$method_name = "__get_{$name}";
if ( method_exists( $this, $method_name ) ) return $this->$name = $this->$method_name();
}
}


class LazyClassRegistry extends BaseClass
{
public $cachedXml = null;


public function getXml()
{
if ( $this->cachedXml === null ) $this->cachedXml = $this->__get_xml();
return $this->cachedXml;
}
}


class NonLazyClass extends BaseClass
{
public function getXml()
{
return $this->__get_xml();
}
}