feature in an object. In a Memento pattern there are three

objects:

Originator: This is the object that has an internal state.

Caretaker: This is the object that can change the state of

Originator. But it wants to have control over rolling back

the change.

Memento: This is the object that Caretaker gets from

Originator, before making and change. If Caretaker wants

to Rollback the change it gives Memento back to

Originator. Originator can use Memento to restore its own

state to the original state.

E.g. One good use of memento is in online Forms. If we

want to show to user a form pre-populated with some

data, we keep this copy in memento. Now user can

update the form. But at any time when user wants to reset

the form, we use memento to make the form in its original

pre-populated state. If user wants to just save the form

we save the form and update the memento. Now onwards

any new changes to the form can be rolled back to the

last saved Memento object.

https://refactoring.guru/design-patterns/memento