Factory Method Design Pattern example in Go (GoLang).

factory_method.go

package storage

import (
	"errors"
	"io"
)

// Product interface

type Storage interface {
	Open(string) (io.ReadWriteCloser, error)
}

// Concrete product: In Memory Storage

type inMemory struct { /* ... */ }

func newInMemory() (*inMemory, error) { /* ... */ }

func (i *inMemory) Open(string) (io.ReadWriteCloser, error) {
	// ...
}

// Concrete product: Disk Storage

type disk struct { /* ... */ }

func newDisk() (*disk, error) { /* ... */ }

func (d *disk) Open(string) (io.ReadWriteCloser, error) {
	// ...
}

// Factory

type StorageType string

const (
	StorageTypeInMemory StorageType = "Storage In Memory"
	StorageTypeDisk                 = "Storage Disk"
)

func New(t StorageType) (Storage, error) {
	switch t {
	case StorageTypeInMemory:
		return newInMemory()
	case StorageTypeDisk:
		return newDisk()
	// Add other concrete types here...
	}
	return nil, errors.New("invalid storage type")
}