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Date: Fri, 23 Nov 2007 09:18:05 +0000
Reply-To: RQuadling@GoogleMail.com
To: "Marco Kaiser" <marco.kaiser@gmail.com>
Cc: "PHP Developers Mailing List" <internals@lists.php.net>
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References: <4740C654.3020302@digitalsandwich.com>
	 <474130B3.9070303@digitalsandwich.com> <4741DC81.6000506@zend.com>
	 <4741D574.2020800@digitalsandwich.com> <474247A2.5050301@zend.com>
	 <4741D9D1.6030106@digitalsandwich.com> <47424B4F.2@zend.com>
	 <4743CED7.5050402@avalon.aut.bme.hu>
	 <a2b4d2820711221229o2debeb30leb4679e316656ecc@mail.gmail.com>
	 <a2b4d2820711221240y3742606ar4cc6a2e84d6fda07@mail.gmail.com>
Subject: Re: [PHP-DEV] late static binding php6
From: rquadling@googlemail.com ("Richard Quadling")

On 22/11/2007, Marco Kaiser <marco.kaiser@gmail.com> wrote:
> Hi again,
>
> to explain the main idea a bit more, the code below work and moves the
> main getInstance function from the class and its possible to abstract
> this.
> it would be cool to get the protected property also into the abstract
> class. Any idea or maybe a solution in the near future?
>
> <?php
> abstract class singleton
> {
>         static public function getInstance()
>         {
>             $caller = get_called_class();
>             if (!static::$_instance instanceof $caller) {
>             static::$_instance = new $caller;
>             }
>
>             return static::$_instance;
>         }
> }
>
> class foo extends singleton {
>         static protected $_instance = null;
> }
>
> class bar extends singleton {
>         static protected $_instance = null;
> }
>
> var_dump(foo::getInstance());
> var_dump(bar::getInstance());
> var_dump(foo::getInstance());
> var_dump(bar::getInstance());
> ?>
>
> On Nov 22, 2007 9:29 PM, Marco Kaiser <marco.kaiser@gmail.com> wrote:
> > Hi List,
> >
> > just to drop my note here, i asked (i think) 2 years ago for such a
> > feature to automate my singleton pattern. Not with late static
> > bindings this is possible.
> >
> > <?php
> > class singleton
> > {
> >         static protected $_instance = null;
> >
> >         static public function getInstance()
> >         {
> >             $caller = get_called_class();
> >             if (!static::$_instance instanceof $caller) {
> >             static::$_instance = new $caller;
> >             }
> >
> >             return static::$_instance;
> >         }
> > }
> >
> > class foo extends singleton
> > {
> > }
> >
> > var_dump(foo::getInstance());
> > var_dump(foo::getInstance());
> > ?>
> >
> > i think this will also drop much redundant code from some frameworks. :)
> > So this is one of my examples that helps much.
> >
> >
> > --
> > Marco Kaiser
> >
>
>
>
> --
> Marco Kaiser

<?php
abstract class singleton
{
       static protected $_instance = null;
       static public function getInstance()
       {
           $caller = get_called_class();
           if (!static::$_instance instanceof $caller) {
           static::$_instance = new $caller;
           }

           return static::$_instance;
       }
}

class foo extends singleton {
}

class bar extends singleton {
}

var_dump(foo::getInstance());
var_dump(bar::getInstance());
var_dump(foo::getInstance());
var_dump(bar::getInstance());
?>

returns ...

object(foo)#1 (0) {
}
object(bar)#2 (0) {
}
object(foo)#1 (0) {
}
object(bar)#2 (0) {
}

in PHP 5.3.0-dev (cli) (built: Nov 20 2007 08:19:12)

I think this is great! Well done everyone. Unless I've completely
missed the point.


-- 
-----
Richard Quadling
Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731
"Standing on the shoulders of some very clever giants!"