Memento

package main

import (

        "fmt"

)

/****************************************************************************

 * Structure with Memento functions                                         *

 ****************************************************************************/

// Carrier is a structure with various properties

type Carrier struct {

        property1 uint

        property2 uint

        flag1     bool

}

// Clone is to create a memento of the Carrier object itself

func (c *Carrier) Clone() *Carrier {

        return &Carrier{

                property1: c.property1,

                property2: c.property2,

                flag1:     c.flag1,

        }

}

// Assimilate is to restore the Carrier object based on its mememto copy

func (c *Carrier) Assimilate(a *Carrier) {

        c.property1 = a.property1

        c.property2 = a.property2

        c.flag1 = a.flag1

}

// Print is to print the current properties' value

func (c *Carrier) Print() {

        fmt.Printf("property1: %v\n", c.property1)

        fmt.Printf("property2: %v\n", c.property2)

        fmt.Printf("flag1: %v\n", c.flag1)

        fmt.Printf("===============\n")

}

/****************************************************************************

 * Safekeeper                                                               *

 ****************************************************************************/

// SandboxConfig is the safekeeper structure to protect the memento copy of

// the Carrier objects.

type SandboxConfig struct {

        targets  []*Carrier

        mementos []*Carrier

}

// NewSandbox creates a new SandboxConfig object

func NewSandbox() *SandboxConfig {

        return &SandboxConfig{

                targets:  []*Carrier{},

                mementos: []*Carrier{},

        }

}

// Mementorize is to make a given Carrier to save its memento copy into the

// sandbox.

func (s *SandboxConfig) Mementorize(c *Carrier) {

        clone := c.Clone()

        s.targets = append(s.targets, c)

        s.mementos = append(s.mementos, clone)

}

// Restore is to restore all Carriers' values back to its original carrier.

func (s *SandboxConfig) Restore() {

        for i := range s.targets {

                x := s.targets[i]

                x.Assimilate(s.mementos[i])

        }

        s.targets = []*Carrier{}

        s.mementos = []*Carrier{}

}

func main() {

        s := NewSandbox()

        c := &Carrier{

                property1: 50,

                property2: 25,

                flag1:     true,

        }

        c.Print()

        s.Mementorize(c)

        c.property1 = 2342

        c.property2 = 2352

        c.flag1 = false

        c.Print()

        s.Restore()

        c.Print()

}

// Output:

// property1: 50

// property2: 25

// flag1: true

// ===============

// property1: 2342

// property2: 2352

// flag1: false

// ===============

// property1: 50

// property2: 25

// flag1: true

// ===============