XOOPS' early data persistence architecture was based on the Data Mapper pattern, with two abstract classes to aid in the class development XoopsObject and XoopsObjectHandler
XoopsObject: abstract class of Data Object
XoopsObjectHandler: Mapper. An abstract class that saves XoopsObject in DB or rebuilds XoopsObject from DB
The idea behind them is that a class can extend XoopsObject to describe an object, whereas extending XoopsObjectHandler will give more like an interface for handling the objects, i.e. get, insert, delete and create objects.
E.g. for a
ThisObject class, you can make a
ThisObjectHandler to get, insert, delete and create
The advantages of extending these two classes are for XoopsObject:
Automatic access (inheritance) to methods, easing the assignment/retrieval of variables
Automatic access to methods for cleaning/sanitizing variables
and for XoopsObjectHandler:
A place to put all those functions working with more than one object i.e. (e.g. a "getAllObjects()" function).
These functions will become easier to track down in the file system (since they are connected to a class, it is just a matter of finding the class and not going through the function files in the module/core/PHP native in search for it.
An additional idea is that the XoopsObjectHandler-extending class should be a Data Access Object, i.e. the class, which handles database calls - and leaving the XoopsObject-extending class to have object-describing methods, such as methods which handle and manipulate variables, calling methods on the handler for retrieving, updating and inserting data in the database.
In XOOPS 2.3 we've added a new enhanced version of the XoopsObjectHandler, the XoopsPersistableObjectHandler, that incorporated features/characteristics from the Repository Pattern