Struct

• Go does not have classes

• See Methods.go to see how to define methods for a given struct

• You can declare a method on non-struct types, too.

• In Methods2.go we see a numeric type MyFloat with an Abs method

• You can only declare a method with a receiver whose type is defined in the same package as the method. You cannot declare a method with a receiver whose type is defined in another package (which includes the built-in types such as int).

Pointer receiver

• There are two reasons to use a pointer receiver.

  • The first is so that the method can modify the value that its receiver points to.

  • The second is to avoid copying the value on each method call. This can be more efficient if the receiver is a large struct, for example.

In PointerReceiver.go both Scale and Abs are with receiver type *Vertex, even though the Abs method needn't modify its receiver.

In general, all methods on a given type should have either value or pointer receivers, but not a mixture of both.