In article <1168250213.972762.77460@s80g2000cwa.googlegroups. com>,
comp.lang.php <phillip.s.powell@gmail.comwrote:
Quote:
[PHP]
<?
class EditResultGenerator extends MethodGeneratorForActionPerformer {
>
/**
* Create an instance of itself if $this does not yet exist as an
EditResultGenerator class object
*
* @access private
* @see is_class
*/
function &generateSelf() { // STATIC VOID METHOD
if (!is_object($this) || @!is_class($this, 'EditResultGenerator')) {
$this->self =& new EditResultGenerator();
} else {
$this->self =& $this;
}
}
>
}
?>
[/PHP]
>
This self-generating function serves a purpose to ensure that if part
of the application does this:
>
[PHP]
<?
EditResultGenerator::getResult();
?>
[/PHP]
>
That it will work *exactly* the same as if I did this:
>
[PHP]
<?
$edit =& new EditResultGenerator();
$result = $edit->getResult();
?>
[/PHP]
>
However, I cannot change hundreds of lines of code from the former to
the latter just to ensure instantiation is uniform, so I'm stuck with
the fact that I have to generate a $this->self EditResultGenerator
class object if $this does not exist, otherwise, $this->self must be
*absolutely identical* to $this, in fact, be a reference!
>
This works beautifully in PHP 4.3+, but bombs in PHP 5.2.
>
How can I get it to work in PHP 5.2+?
>
Phil
>
For a PHP5 implementation, I wouldn't modify within
EditResultGenerator directly per sae. I would add a Singleton class and
then reference that as needed. For example..
<?php
class Singleton{
private static $instances = array();
private function __construct(){}
public function getInstance($class){
if(!array_key_exists($class, self::$instances)){
// PHP5 creates by reference "=&" automatically
self::$instances[$class] = new $class;
}
return self::$instances[$class];
}
public final function __clone(){
trigger_error( "Cannot clone Singleton class", E_USER_ERROR );
}
}
// Modified this class as a demo...
class MethodGeneratorForActionPerformer{
private $signature;
function __construct(){
$this->signature = rand();
}
function getUnique(){
echo "Unique signature is ", $this->signature,"\n";
}
}
class EditResultGenerator extends MethodGeneratorForActionPerformer {
// your other methods...
}
// Demo for getting single instance
$edit1 = Singleton::getInstance('EditResultGenerator');
$edit2 = Singleton::getInstance('EditResultGenerator');
// Test that they are the same
$edit1->getUnique();
$edit2->getUnique();
?>
--
Koncept <<
"The snake that cannot shed its skin perishes. So do the spirits who are
prevented from changing their opinions; they cease to be a spirit." -Nietzsche
