Proxy Pattern

In object-oriented programming, the Proxy Pattern is a design pattern that provides a surrogate or placeholder for another object to control access to it. A Proxy can interface to anything that has an expensive or complex initialization step, for example, a large object in memory, file, or a network connection.

This pattern involves a single class, known as the proxy, which represents the functionality of another class. The proxy can provide a level of indirection to the object and can add additional behavior without the client knowing about it.

The Proxy pattern is essentially about controlling and managing access to a particular object, and is typically used in situations where creating an object is expensive in terms of time, resources, or complexity.

There are several types of proxy patterns, including:

1. Virtual Proxy: In place of a complex or heavy object which takes lots of memory and time to load, we can use a simpler proxy.

2. Remote Proxy: Provides a local representation for an object that resides in a different address space.

3. Protective Proxy: Controls access to a sensitive object.

4. Smart Reference: Adds additional actions when an object is accessed.