Memento Flashcards
1
Q
Intent
A
Without breaking encapsulation, capture and externalize an object’s internal state.
2
Q
Motivation
A
Store a snapshot of the internal state of another object, originator
3
Q
Structure
A
4
Q
Participants
A
- Memento
- stores the internal state of the Originator
- Mementos have two interfaces: narrow interface (Caretaker) and wide interface (Originator)
- Originator
- creates a memento containing a snapshot of its current internal state
- uses the memento to restore its internal state
- Caretaker
- responsible for the memento’s safekeeping
- never examines or operates on the contents of memento
5
Q
Related Patterns
A
- Command
- Iterator
6
Q
Collaborations
A
Caretaker (client) can request a memento from the originator (to save a snapshot) and pass a memento back to the originator (to restore previous state)
7
Q
AKA
A
Token
8
Q
What is the role of a Caretaker
A
Setting and getting the memento.
9
Q
Does the Caretaker have access to the contents of a memento?
A
No
10
Q
Which participant stores the internal state of which object?
A
Memento stores the internal state of Originator.
11
Q
Mementos have two interfaces, narrow and wide. Which participants are what?
A
- Originator* is wide interface.
- Caretaker* is narrow interface.
