Proxy design pattern
We'll start the final chapter on structural patterns with the Proxy pattern. It's a simple pattern that provides interesting features and possibilities with very little effort.
Description
The Proxy pattern usually wraps an object to hide some of its characteristics. These characteristics could be the fact that it is a remote object (remote proxy), a very heavy object such as a very big image or the dump of a terabyte database (virtual proxy), or a restricted access object (protection proxy).
Objectives
The possibilities of the Proxy pattern are many, but in general, they all try to provide the same following functionalities:
Hide an object behind the proxy so the features can be hidden, restricted, and so on
Provide a new abstraction layer that is easy to work with, and can be changed easily
Example
For our example, we are going to create a remote proxy, which is going to be a cache of objects before accessing a database. Let's imagine that we have a database with many users...
