Methods and Interfaces

Part of the Go course

The last lesson taught you how to bundle related fields into a struct, but a struct on its own only holds data, it has no behavior. If you want a Rectangle to know how to compute its own area, you either write a plain function that takes a Rectangle as an argument, or you attach the behavior to the type itself so it travels together with the data.

A method is an ordinary function with one extra ingredient: a receiver, a named variable of a specific type that sits in its own parentheses between the word func and the method's name. That receiver is what lets you write r.Area() instead of Area(r), the same way a remote control that has been paired to one specific television only ever controls that one television, no matter which button you press on it.