Advanced ActionScript 3 with Design Patterns

Chapter 11. Memento Pattern

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• Using Mementos to Make Actions Undoable in the Proximity game 173

• Using Mementos to Make Actions Redoable in the Proximity game 177

• Summary 180

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The Memento pattern is a way of recording an object’s current state without breaking the rules of encapsulation. The rules of encapsulation say that an object should manage its own state, and that it should allow external objects to influence its state only through a well-defined API. For example, it is perfectly acceptable for a class to define a setter method that changes the value of a private property. However, it would be bad design to use public properties that can be set without going through a method of the class. Public ...