Editing Memento pattern (section)

== Structure ==
=== UML class and sequence diagram ===
[[File:w3sDesign Memento Design Pattern UML.jpg|frame|none|A sample UML class and sequence diagram for the Memento design pattern.<ref>{{cite web|title=The Memento design pattern - Structure and Collaboration|url=http://w3sdesign.com/?gr=b06&ugr=struct|website=w3sDesign.com|access-date=2017-08-12}}</ref>]]
In the above UML class diagram, 
the <code>Caretaker</code> class refers to the <code>Originator</code> class 
for saving (<code>createMemento()</code>) and restoring (<code>restore(memento)</code>) originator's internal state.
<br>
The <code>Originator</code> class implements 
<br>
(1) <code>createMemento()</code> by creating and returning a <code>Memento</code> object that stores originator's current internal state
and 
<br>
(2) <code>restore(memento)</code> by restoring state from the passed in <code>Memento</code> object.
<br>

The [[Unified Modeling Language|UML]] sequence diagram
shows the run-time interactions: 
<br>
(1) Saving originator's internal state: The <code>Caretaker</code> object calls <code>createMemento()</code> on the <code>Originator</code> object,
which creates a <code>Memento</code> object, saves 
its current internal state (<code>setState()</code>), and returns the <code>Memento</code> to the <code>Caretaker</code>.
<br>
(2) Restoring originator's internal state: The <code>Caretaker</code> calls <code>restore(memento)</code> on the <code>Originator</code> object and specifies the <code>Memento</code> object that stores the state that should be restored. The <code>Originator</code> gets the state (<code>getState()</code>) from the <code>Memento</code> to set its own state.