The line between proxy and decorator

At this point in the book, you might have some legitimate doubts about the differences between the Proxy and the Decorator patterns. These two patterns are indeed very similar and they can sometimes be used interchangeably.

In its classic incarnation, the Decorator pattern is defined as a mechanism that allows us to enhance an existing object with new behavior, while the Proxy pattern is used to control access to a concrete or virtual object.

There is a conceptual difference between the two patterns, and it's mostly based on the way they are used at runtime.

You can look at the Decorator pattern as a wrapper; you can take different types of objects and decide to wrap them with a decorator to enhance their capabilities with extra functionality. A proxy, instead, is used to control the access to an object and it does not change the original interface. For this reason, once you have created a proxy instance, you can pass it over to...