How to Define Methods on Types in Go

You define methods on types in Go by declaring a function with a receiver argument that matches the type name. The receiver appears in parentheses between the func keyword and the method name.

type MyType struct {
    Value int
}

func (m *MyType) Double() int {
    return m.Value * 2
}

Use a pointer receiver (*MyType) if the method needs to modify the struct's fields; use a value receiver (MyType) if it only reads data.

Defining a method is like attaching a specific action directly to a data structure so you can call it using dot notation. You choose whether the action can change the data (pointer receiver) or just read it (value receiver). It is similar to adding a button to a remote control that only works with that specific TV.