Array of inherited structs in Go Lang

Question

Recently I have started building a chess game in GoLang and one issue I'm facing is storing different characters (i.e. Pawn, Knight, King) in a single array.

package main

import "fmt"

type character struct {
    currPosition [2]int
}

type Knight struct {
    c character
}

func (K Knight) Move() {
    fmt.Println("Moving Kinght...")
}

type King struct {
    c character
}

func (K King) Move() {
    fmt.Println("Moving King...")
}

In the above case, can we have Knight and King in the same array since they are inherited from the same base class?

Like

characters := []character{Knight{}, King{}}

Answer 1

Use basic interfaces for polymorphism.

type character interface {
    Move()
    Pos() [2]int
}

type Knight struct {
    pos [2]int
}

func (K *Knight) Move() {
    fmt.Println("Moving Kinght...")
}

func (k *Knight) Pos() [2]int { return k.pos }

type King struct {
    pos [2]int
}

func (k *King) Move() {
    fmt.Println("Moving King...")
}

func (k *King) Pos() [2]int { return k.pos }

The following statement compiles with this changes:

characters := []character{&Knight{}, &King{}}

Also, you probably want pointer receivers as in this example.

Answer 2

Go doesn't have classes and inheritance. Compile-time polymorphism is not possible in Go (since method overloading is not supported). It only has Runtime Polymorphism. But it has a concept called composition. Where the struct is used to form other objects.

You can read here why Golang doesn't have inheritance like OOP concepts in other programming languages. https://www.geeksforgeeks.org/inheritance-in-golang/

OR

Instead of implementing chess pieces separately, you can have single struct for all of them with different values of respective attributes.

// Piece represents a chess piece
type Piece struct {
    Name   string
    Color  string
    PosX   int
    PosY   int
    Moves  int
    Points int
}

type Board struct {
    Squares [8][8]*Piece
}

func (b *Board) MovePiece(p *Piece, x, y int){
      // Your logic to move a chess piece.
}

...
// and make objects for Piece struct as you build the board.
king := &Piece{Name: "King", Color: "White", Points: 10}

OR

You must use interface if you want to implement chess pieces separately.