Proxy Pattern

1. Introduction

The Proxy Pattern is a structural design pattern that provides an object representing another object. This allows you to control access to the original object, enabling functionalities like lazy loading, access control, and logging.

2. Definition

A proxy is an object that acts as a substitute for another object to control access to it. It can provide additional functionality before or after delegating operations to the real subject.

3. Types of Proxy Patterns

• Virtual Proxy: Delays the creation and initialization of a resource until it is needed.
• Remote Proxy: Represents an object that is in a different address space (e.g., over a network).
• Protection Proxy: Controls access to the original object by providing different access rights.

4. Implementation

Below is an example of a Proxy Pattern implementation in Python:

class RealSubject:
    def request(self):
        return "RealSubject: Handling request."

class Proxy:
    def __init__(self, real_subject):
        self._real_subject = real_subject

    def request(self):
        # Additional operations can be performed here
        return self._real_subject.request()

# Client code
real_subject = RealSubject()
proxy = Proxy(real_subject)
print(proxy.request())
                

5. Best Practices

• Use proxies to implement lazy initialization for resource-heavy objects.
• Consider using remote proxies for network communication to handle serialization and deserialization.
• Implement protection proxies to enforce security and access control policies.

6. FAQ