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Scala Design Patterns

You're reading from   Scala Design Patterns Design modular, clean, and scalable applications by applying proven design patterns in Scala

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Product type Paperback
Published in Apr 2018
Publisher Packt
ISBN-13 9781788471305
Length 396 pages
Edition 2nd Edition
Languages
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Author (1):
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Ivan Nikolov Ivan Nikolov
Author Profile Icon Ivan Nikolov
Ivan Nikolov
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Table of Contents (14) Chapters Close

Preface 1. The Design Patterns Out There and Setting Up Your Environment 2. Traits and Mixin Compositions FREE CHAPTER 3. Unification 4. Abstract and Self Types 5. Aspect-Oriented Programming and Components 6. Creational Design Patterns 7. Structural Design Patterns 8. Behavioral Design Patterns – Part One 9. Behavioral Design Patterns – Part Two 10. Functional Design Patterns – the Deep Theory 11. Applying What We Have Learned 12. Real-Life Applications 13. Other Books You May Enjoy

The memento design pattern

Depending on the software we are writing, we might have a requirement to be able to restore the state of an object back to its previous state.

The purpose of the memento design pattern is to provide the ability to execute an undo action in order to restore an object to a previous state.

The original memento design pattern is implemented with the help of three main objects:

  • Originator: The object whose state we want to be able to restore
  • Caretaker: The object that triggers the changes to the originator object and uses the memento objects for rollback, if needed
  • Memento: The object that carries the actual state of the originator and can be used to restore to one of the previous states

It is important to know that the memento object can be handled only by the originator. The caretaker and all other classes can just store it and nothing else.

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