Proxy pattern explained

- [Instructor] So, according to the Gang of Four,…the intent for the proxy pattern…is to provide a surrogate or placeholder for another object…to control access to it.…So, what does that really mean?…Simply said, it provides objects that references…other objects for their functionality.…Let's go ahead and take a look at the class diagram.…Now at the middle in the top,…we have a subject, and that defines the common interface…for RealSubject and Proxy so that the proxy can be used…anywhere a real subject is expected.…

At the bottom left-hand side, we have our real subject,…and that defines the real object that the proxy represents.…And to the right of that is the proxy,…which maintains a reference that lets the proxy…access the real subject.…Now to make sense of this,…we're going to demonstrate the proxy pattern…or a math object that's represented…by a calculate proxy object.…That is, where's going to have a proxy that points…to math functionalities…such as addition, subtraction, and multiplication,…but the client won't know about it.…