[Typo3-dev] singletons instead of pre-loaded objects

[Robert Lemke]

On Mon, 2004-08-09 at 20:47, Martin T. Kutschker wrote:
> Why? You need some place to store the object references. As options I 
> see either a global array, a master object known to be loaded or factory 
> objects for every singleton (the object has a method with a static var 
> as storage).

Because the recommended way for implementing the Singleton pattern is
not to store instantiation information in a global variable but use a
static variable within the class itself (at least that's what I remember
from the GOF book). 

So what I meant is what you mentioned as option no. 3 (method with
static var), although I don't understand yet why it's called factory
objects.

But with you method, how would I access the object so it could be
created automatically? 

> > function &makeInstance($className)	{
> >    $realClassName =  t3lib_div::makeInstanceClassName($className);
> >    if (function_exists ($realClassName.'::getInstance')) {
> >          // Must be done this way, because call_user_func does not
> >          // return references:
> >       $tmpObj = call_user_func (array ($realClassName, 'getInstance));
> >       return $tmpObj->getInstance();
> >    } else {
> >       new $realClassName;
> >    }
> > }

> But this way you create every time a temp. object, so it's pointless. 
> The point is to avoid object creation.

You mean the $tmpObj? It's true, this would be an unneccessary instance. 
Does this work? :

if (function_exists ($realClassName.'::getInstance')) 
     return $realClassName::getInstance();
   } else {
     new $realClassName;
   }

-- 
robert

"They placed me on this earth without a manual. 
 And I dare to say, I’m doing just fine without ;)"