Re: [fw-mvc] Re: [fw-general] Bootstrap Resource usage in model - best practice advice please

> Storing the default cache instance with a unique key with Zend_Registry, 

> which actually follows the Singleton pattern, is just that.

Zend_Registry uses Martin Fowler's Registry pattern. Not singleton.

> If you have a model class that is equipped with a method that returns a cache instance, 

> how would returning the cache be handled?

> Retrieve it from Zend_Registry? Then it's Singleton.

No, it's not. Passing object by reference doesn't mean singleton. 

> Check, if a cache instance has been stored in a non-static designated property of the model instance, 

> if not, create and store it, return it? Then you'd have a cache instance for every model instance.

You're wrong. As you know, objects since PHP5 are passed by reference. So you will have most probably only one object instance, referenced to each model, except you prefer otherwise. And that's the way I would prefer.

--
Regards,
Vladas Diržys

On Sun, Jan 17, 2010 at 21:17, Andreas Möller <localheinz@l8m.de> wrote:

Ok. It might depend on business logic. But singleton is only for one
thing good: it ensures, that there will be only one instance of this
object in a life cycle.

At most there will be an instance of a class, which is an object, but not of an object.

So with singleton you would exclude possibility to bypass other caching
objects. But non-singleton solution doesn't mean that you will have
multiple instances.

How many would you have, then? And how would you retrieve it - stored with Zend_Registry? Storing the default cache instance with a unique key with Zend_Registry, which actually follows the Singleton pattern, is just that.

Singleton makes also unit testing more difficult.

Can't say anything about unit testing - haven't explored it yet.

In other words, I don't see the benefit of singleton pattern, only
loosing possibility to have multiple instances if its needed, and making
it more difficult for unit testing

If you have a model class that is equipped with a method that returns a cache instance, how would returning the cache be handled?

Retrieve it from Zend_Registry? Then it's Singleton.

Check, if a cache instance has been stored in a non-static designated property of the model instance, if not, create and store it, return it? Then you'd have a cache instance for every model instance.

Check, if a cache instance has been stored in a designated static property of the model instance, if not, create and store it, then return it? Then you'd have a single cache instance for all model instances subclassing the base model class in which this static property is made available, so, if all of your models extend this base class, your model cache instance would be a Singleton.

But, when using a cache, I believe you are interested in increasing the performance of your application rather than just using caching because it sounds like fun. So, you will rather want to work with the least number of cache instances satisfying your needs rather than wasting resources by creating countless of them.


Best regards,

Andreas