Equivalence of abstract classes/methods (Java) in Google Go

Question

I am new to Go and I'm wondering how I can implement a structure similar to abstract classes & methods in Java. In Java, I'd do the following:

abstract class A{

 static method1(){
  ...
  method2();
  ...
 }

 abstract method2();

}

class B extends A{

 method2(){
  ...
 }

}

class C extends A{

 method2(){
  ...
 }

}

I know about interfaces and structs. I could build an interface and then a struct to implement method1. But what about method2? I know that I can embed one interface in another and also a struct as a field of another struct. But I don't see a way to implement my structure with those methods.

The only solution I see is to implement method1 both in class B and class C. Isn't there another way?

Note: of course in my case it's not just one method. Also I've got a hierarchy of abstract classes and don't really want to move everything down to the 'subclasses'.

The examples I've found on the internet are mostly with only one method per interface. It would be great if one of you guys could give me a hint here! Thanks.

Answer 1

Since Go does not have static methods in the OOP sense, you often see those types of methods being implemented as package level functions:

package mypackage

func() Method1() { ... } // Below I will call it Function instead

Such package level functions would then take an interface as an argument. Your code would in that case look something like this:

package main

import "fmt"

type Methoder interface {
    Method()
}

func Function(m Methoder) {
    m.Method()
}

type StructB struct{}

func (s *StructB) Method() { fmt.Println("StructB") }

type StructC struct{} // You can do some "inheritance" by embedding a base struct

func (s *StructC) Method() { fmt.Println("StructC") }

func main() {    
    b := &StructB{}
    Function(b)    
}

Output:

StructB