I’m sure if you are a Magento developer, you’ve seen or used a lot of these types of methods: Mage::app(), Mage::getModel(), Mage::getSingleton(), etc. I’d like to explain how and why these work if you are unaware.

First, if you open up app/Mage.php, you’ll notice that the class declaration is final class Mage. The ‘final’ php keyword prevents this class from being overridden (extended). Second, you’ll notice that every function in the class is a static function, for instance: public static function getVersion(). A static function basically means that you do not need to instantiate the class/object to use the method.

I will list out some of the main, most useful methods available here. If you want to see the others, just open up app/Mage.php and have a look. You can call these anywhere within your application:

• Mage::getVersion()
  ????Returns your current Magento version.
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• Mage::getModel($modelClass = '', $arguments = array())
  ????Returns a new model object.
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• Mage::helper($name)
  ????Returns a helper object.
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• Mage::log($message, $level = null, $file = '', $forceLog = false)
  ????Logging tool. If you only pass in a message, it logs to var/log/system.log, if you have logging enabled.
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• Mage::app()
  ????Initialize a Magento application object.
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• Mage::getStoreConfig($path, $store = null)
  ????Returns config value by path (basically anything in System >> Configuration).
  ?
• Mage::getBaseUrl($type = Mage_Core_Model_Store::URL_TYPE_LINK, $secure = null)
  ????Returns the base URL by type.
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• Mage::register($key, $value)
  ????Registers a new variable in the registry.
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• Mage::unregister($key)
  ????Unregisters a variable in the registry.
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• Mage::registry($key)
  ????Returns a value from the registry by the given key.
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• Mage::getBaseDir($type = 'base')
  ????Returns the root absolute path. You can of course change which website by passing in the code.
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• Mage::getModuleDir($type, $moduleName)
  ????Returns the absolute path of a given module.
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• Mage::getStoreConfigFlag($path, $store = null)
  ????Returns a config flag by path.
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• Mage::getConfig()
  ????Returns a config instance.
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• Mage::getUrl($route = '', $params = array())
  ????Generates a url by route and parameters.
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• Mage::getDesign()
  ????Returns a design package singleton.
  ?
• Mage::dispatchEvent($name, array $data = array())
  ????Dispatches an event in Magento.
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• Mage::getSingleton($modelClass = '', $arguments = array())
  ????Returns a model object singleton.
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• Mage::getResourceModel($modelClass, $arguments = array())
  ????Returns a resource model object.
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• Mage::throwException($message, $messageStorage = null)
  ????Throw an exception, the Magento way.
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• Mage::setIsDeveloperMode($mode)
  ????Turns developer mode on or off ($mode should be true or false).
  ?
• Mage::getIsDeveloperMode()
  ????Returns if developer mode is enabled or not