undostack allows operations to be done (executed) and keeps track of them in order to be able to undo and redo them.
An Operation can consist of one or more Actions, whose Do() methods are called when the opration is done/redone and whose Undo() methods are called in reverse order when the operation is undone.
Action is the interface that wraps the Do() and Undo() method that must be implemented for arbitrary actions:
type Action interface {
Do() error
Undo() error
}Not quite serious example with an operation that holds two actions:
package main
import (
"fmt"
"github.com/mfmayer/undostack"
)
// Implement welcome action
type welcomeAction struct{}
func (wa *welcomeAction) Do() error {
fmt.Println("Welcome my friend.")
return nil
}
func (wa *welcomeAction) Undo() error {
fmt.Println("Go away, I don't like you.")
return nil
}
// Implement action to offer a seat
type offerSeatAction struct{}
func (sfa *offerSeatAction) Do() error {
fmt.Println("Please have a seat.")
return nil
}
func (sfa *offerSeatAction) Undo() error {
fmt.Println("Please stand up.")
return nil
}
func main() {
// initalize the undo stack
undoStack := undostack.UndoStack{}
// create the receive operation and add the actions welcome and offer a seat
receiveOperation := undostack.Operation{
Name: "Receive Guest",
Actions: []undostack.Action{
&welcomeAction{},
&offerSeatAction{},
},
}
// Do, Undo and Redo the opearion
fmt.Println("# Do receive:")
undoStack.Do(&receiveOperation)
fmt.Println("\n# Undo receive:")
undoStack.Undo()
fmt.Println("\n# Redo receive:")
undoStack.Redo()
}