Go Example

package main

type caretaker struct {
    mementoArray []*memento
}

func (c *caretaker) addMemento(m *memento) {
    c.mementoArray = append(c.mementoArray, m)
}

func (c *caretaker) getMemento(index int) *memento {
    return c.mementoArray[index]
}

package main

type memento struct {
    state string
}

func (m *memento) getSavedState() string {
    return m.state
}

package main

type originator struct {
    state string
}

func (e *originator) createMemento() *memento {
    return &memento{state: e.state}
}

func (e *originator) restoreMemento(m *memento) {
    e.state = m.getSavedState()
}

func (e *originator) setState(state string) {
    e.state = state
}

func (e *originator) getState() string {
    return e.state
}

package main

import "fmt"

func main() {

    caretaker := &caretaker{
        mementoArray: make([]*memento, 0),
    }

    originator := &originator{
        state: "A",
    }

    fmt.Printf("Originator Current State: %s\n", originator.getState())
    caretaker.addMemento(originator.createMemento())

    originator.setState("B")
    fmt.Printf("Originator Current State: %s\n", originator.getState())
    caretaker.addMemento(originator.createMemento())

    originator.setState("C")
    fmt.Printf("Originator Current State: %s\n", originator.getState())
    caretaker.addMemento(originator.createMemento())

    originator.restoreMemento(caretaker.getMemento(1))
    fmt.Printf("Restored to State: %s\n", originator.getState())

    originator.restoreMemento(caretaker.getMemento(0))
    fmt.Printf("Restored to State: %s\n", originator.getState())

}

originator Current State: A
originator Current State: B
originator Current State: C
Restored to State: B
Restored to State: A