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As with the previous
example in the declaration of the getInstance() method, we make the method
return a reference and we define it as static in the doctags.
An extension of this mechanism is to allow instantiation of subclasses. A good
example of this is the core JDocument class that can instantiate JDocumentError,
JDocumentFeed, JDocumentHTML, JDocumentPDF, or JDocumentRAW (located at
libraries/joomla/document).
In this example, we will attempt something similar; assume that the subclasses are
located in the root of a component and named with the prefix SomeClass:
/**
* Returns a reference to the global SomeClass object
*
* @access public
* @static
* param string A string
* @return mixed A SomeClass object, false on failure
*/
function &getInstance($foo)
{
static $instances;
// prepare static array
if (!$instances)
{
$instances = array();
}
$foo = (string)$foo;
$class = 'SomeClass'.$foo;
$file = strtolower($foo).'.php';
if (empty($instances[$foo]))
{
if (!class_exists($class))
{
// class does not exists, so we need to find it
jimport('joomla.


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