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Learning Scala Programming

You're reading from   Learning Scala Programming Object-oriented programming meets functional reactive to create Scalable and Concurrent programs

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Product type Paperback
Published in Jan 2018
Publisher Packt
ISBN-13 9781788392822
Length 426 pages
Edition 1st Edition
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Author (1):
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Vikash Sharma Vikash Sharma
Author Profile Icon Vikash Sharma
Vikash Sharma
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Table of Contents (16) Chapters Close

1. Getting Started with Scala Programming FREE CHAPTER 2. Building Blocks of Scala 3. Shaping our Scala Program 4. Giving Meaning to Programs with Functions 5. Getting Familiar with Scala Collections 6. Object-Oriented Scala Basics 7. Next Steps in Object-Oriented Scala 8. More on Functions 9. Using Powerful Functional Constructs 10. Advanced Functional Programming 11. Working with Implicits and Exceptions 12. Introduction to Akka 13. Concurrent Programming in Scala 14. Programming with Reactive Extensions 15. Testing in Scala 16. Other Books You May Enjoy

Implicit parameters


We use implicit parameters when we want the compiler to help us find a value that's already available for a certain type. We've just seen an example of an implicit parameter when we talked about Future. Why don't we define something similar for ourselves?

We can think of a scenario where we need to show the present date in our application and we want to avoid passing a date's instance explicitly again and again. Instead, we can make the LocalDateTime.now value implicit to the respective functions and let the current date and time be passed as an implicit parameter to them. Let's write some code for this:

import java.time.{LocalDateTime} 
 
object ImplicitParameter extends App { 
 
  implicit val dateNow = LocalDateTime.now() 
 
  def showDateTime(implicit date: LocalDateTime) = println(date) 
   
  //Calling functions! 
  showDateTime 
} 

The following is the result:

2017-11-17T10:06:12.321 

Think of the showDateTime function as the one that needs the date-time's current value...

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