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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

Lazy evaluation

Writing efficient code is an important part of software engineering. A lot of times, we will see cases where an expression is expensive to evaluate due to different possible reasons—database access, complex calculations, and so on. There are cases where we might even be able to exit the application without even evaluating these expensive expressions. This is where lazy evaluation becomes helpful.

Lazy evaluation makes sure that an expression is evaluated only once when it is actually needed.

Scala supports lazy evaluation in a couple of flavors—lazy variables and by-name parameters. We have already seen both in this book the former we saw when we looked at creational design patterns in Chapter 6, Creational Design Patterns, and more specifically, lazy initialization. We saw the latter in a few places, but we encountered it for the first time in Chapter...

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