What is a common purpose of the Proxy design pattern?

What is a common purpose of the Proxy design pattern?

• A. To enforce coding standards.
• B. To provide transparency of representation.
• C. To control access, delay expensive initialization, or add logging/security.
• D. To create object graphs by combining components.

Answer: (C)

A Proxy serves as a stand‑in for another object to control how that object is accessed and used, often adding behavior like delaying creation, logging, or enforcing security. The pattern typically involves the proxy presenting the same interface as the real object and delegating calls to it, but it can perform actions before or after those calls. A classic example is a virtual proxy that delays creating a heavy object (like a large image or database connection) until it’s actually needed, saving resources until demand arrives. It can also act as a protection proxy to check permissions before forwarding requests, or as a logging proxy to record usage. The other options don’t capture this core purpose. Enforcing coding standards is about development processes or tooling, not about controlling access or adding behavior to interactions with an object. The idea of “transparency of representation” touches on the proxy’s invisibility to clients, but the primary reason to use a proxy is the ability to manage access and add costs or protections around the real object, not just to make the representation appear the same.

A Proxy serves as a stand‑in for another object to control how that object is accessed and used, often adding behavior like delaying creation, logging, or enforcing security. The pattern typically involves the proxy presenting the same interface as the real object and delegating calls to it, but it can perform actions before or after those calls. A classic example is a virtual proxy that delays creating a heavy object (like a large image or database connection) until it’s actually needed, saving resources until demand arrives. It can also act as a protection proxy to check permissions before forwarding requests, or as a logging proxy to record usage.

The other options don’t capture this core purpose. Enforcing coding standards is about development processes or tooling, not about controlling access or adding behavior to interactions with an object. The idea of “transparency of representation” touches on the proxy’s invisibility to clients, but the primary reason to use a proxy is the ability to manage access and add costs or protections around the real object, not just to make the representation appear the same.