Adapters

Abstract

One of the major concepts behind Component Architecture is to divide different types of functionality into different components in order to keep the amount of functionality provided by a single component small. Its strength lies in combining these components into a powerful application. In Chapter 2, adapters were defined as components that allow you to extend the functionality of existing components. Adapters play a major role in Component Architecture and in Zope 3, the software based on it.

Adapters are useful when a component needs to work with a certain framework. Instead of requiring the objects the framework works with to provide a certain API, the framework usually tries to adapt the object to one of its own APIs. If an adapter exists for the object, then the framework can work with the object through the adapter. This chapter will demonstrate implementing adapters. Because adapters are an integral part of the Component Architecture, they will frequently appear in later chapters.

We have already worked with a framework using adapters: the Zope publisher. Views are named adapters that add presentation functionality to the objects they present.