Autoloading Of Classes

Currently shop has three autoloaders registered: Composer autoloader, Backwards Compatibility Autoloader and Module Autoloader. They are registered in exactly this order in the file bootstrap.php.

General workflow

If you request a class, then first the Composer autoloader is asked, after that the Backwards Compatibility Autoloader and in the end the Module Autoloader:

@startuml start :<b>Composer Autoloader</b>; if (is there a autoload section in a composer.json?) then (true) :Load class according composer.json autolaod section; stop else (false) :<b>Backwards Compatibility Autoloader</b>; --> if (class can be resolved to the unified namespace equivalent class) then (true) :trigger Compsoer Autoloader; stop else (false) :<b>Module Autoloader</b>; if (class found in module metadata files array?) then (true) :Load class from path defined in metadata; stop else (false) if (class found in module metadata extends array?) then (true) :Create extension chains; stop else (false) :Loads any other registered autoloader or a Class not found fatal error is thrown; stop endif endif endif endif @enduml

Composer Autoloader

It is the first autoloader in line and tries to autoload all namespaced classes, which are configured in the root composer.json file or child composer.json files. An example of a class which would be resolved by this autoloader is OxidEsales\Eshop\Application\Model\Article.

Backwards Compatibility Autoloader

Its purpose is to autoload all deprecated shop classes which are defined in the file Core/Autoload/BackwardsCompatibilityAutoload.php. This is not a real autoloader: If a backwards compatibility class from Core/Autoload/BackwardsCompatibilityAutoload.php is requested, this autoloader searches the Unified Namespace equivalent of the backwards compatible class and hands the request over to the Composer autoloader. If you request e.g. the backwards compatiblity class oxArticle, this autoloader would resolve the class to its unified namespace equivalent OxidEsales\Eshop\Application\Model\Article and trigger the composer autoloader.

Module Autoloader

This autoloader is responsible for loading module classes (defined in metadata as module files and extensions). It first checks if given class exists in any of active modules module file. If so - this class is included and it stops here. If not - it tries to check whether it is an extension of any active module, as modules can extend other module classes. This is also the case when extension is created via new ExtendedClass instead of oxNew, and as ExtendedClass_parent class does not exist, it has to be created at this point.