"Gang of Four" Design Patterns in Magento Core

Question

There are a few very obvious patterns in use in Magento's core, such as:

• Singleton
• Registry
• Event/Observer
• Factory
• Model/View/Controller

But there are others that may be in use in Magento that I'm not aware of such as Actor, Decorator, Strategy patterns.

Is there a reference list of the usage of all pattern types in Magento or how to implement in third party modules that don't unnecessarily replicate built-in functionality of Magento?

Answer 1

There is a list of design patterns which are used in Magento on Stack Overflow

From the article:

The obvious ones are:

Factory:

$product = Mage::getModel('catalog/product');

Singleton:

$category = Mage::getSingleton('catalog/session');

Registry:

$currentCategory = Mage::registry('current_category');

View Helper:

Mage::helper('core');

Prototype:

Mage:getModel('catalog/product')->getTypeInstance();

Object Pool:

$id = Mage::objects()->save($object);
$object = Mage::objects($id);

Iterator:

Mage::getModel('catalog/product')->getCollection();

Event/Listeners:

Mage::dispatchEvent('model_load_before', $params);

EDIT

Active record

$product->save()
$product->getName()

Null object

$collection->getFirstItem()

Lazy loading - collections are loaded when iterated

There are also 5 articles on Ryan Street blog about MVC, Front Controller, Factory, Singleton and Registry in Magento

Edit
I might add that the Magento 'singleton' is more a pseudo-singleton. It's a combination of 'Factory' because Mage::getSingleton() is a factory and 'Registry' because inside the getSingleton() method this is called

self::register($registryKey, self::getModel($modelClass, $arguments))