GoLang method inheritance and overridance

method_override.go

package main
import "fmt"

// Method inheritance in GoLang is particularly interesting:
// 1. If a struct A has an anonymous field of struct B, then an object of A has all the methods from B.
//    Yes, that means you can call those methods of B directly without referring the field name,
//    just as if those methods are native to A. (Refer to the struct Student in the example below.)
// 2. This does not work if the field is named though. (Refer to the struct Employee case in the
//    example below. )
// 3. Then what happens if A has a method whose name overlaps with one of B's methods?
//    3.1. A's method takes priority.
//    3.2. B's method can be referred by using the type name (since anonymous field)
//    (Refer to the Customer use case in the example below).

type Human struct {
	name string
	age int
	phone string
}

type Employee struct {
	who Human
	company string
}

type Student struct {
	Human // anonymous field
	school string
}

type Customer struct {
	Human
	solute string
}

// define a method in Human
func (h *Human) SayHi() {
	fmt.Printf("Hi, I am %s you can call me on %s.\n", h.name, h.phone)
}

func (c *Customer) SayHi() {
	fmt.Printf("Hi, I am your customer %s %s.\n", c.solute, c.name)
}

func main() {
	mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
	sam := Employee{who: Human{"Sam", 45, "111-888-XXXX"}, company: "Golang Inc"}
	smith := Customer{Human{"Smith", 30, "806-888-1234"}, "Mrs."}

	mark.SayHi()

	sam.who.SayHi()
	// sam.SayHi() this does not work, compiler error.

	smith.SayHi()         // call SayHi defined for Customer
	smith.Human.SayHi()   // call SayHi defined for Human
}