Initialization of class members using constructor parameters

Question

I would like to create a class that only holds single-digit numbers.

class onlyLikesSingleDigits(val anyNumber: Seq[Int]) {
  val onlySingleDigits = anyNumber.filter(_ < 10)
}

The idea is you can construct it, and any numbers greater than or equal to 10 that you pass into the constructor would just be discarded.

My implementation looks rather ugly. Can't I do this without using anyNumber? I want to initialize my class using the constructor parameters as input to the filter, not as actual members of the class.

How can I do this with only a single val?

if you want only filtered elements, why not use filtered sequence as constructor argument directly? the example is a bit artificial. — Ashalynd
– Ashalynd, Commented Sep 30, 2014 at 23:27

Community · Accepted Answer · 2017-05-23 10:26:32Z

2

Just remove val from anyNumber and it won't be member of the class. Maybe you'll find this helpful: scala class constructor parameters

edited May 23, 2017 at 10:26

CommunityBot

11 silver badge

answered Sep 30, 2014 at 23:04

Sergey Lihoman

988 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

hellraiser · Accepted Answer · 2014-10-01 07:07:00Z

1

You should better separate the data representation from constructor logic by using Factory pattern.

Data representation

scala> case class OnlyLikesSingleDigits(digits: Seq[Int])

Factory

object DigitsMaker { 
  def apply(anyNums: Seq[Int]) = OnlyLikesSingleDigits(anyNums.filter(_ < 10)) 
}

Usage

scala> val r = DigitsMaker(Seq(4, 12, 5, 76))
r: OnlyLikesSingleDigits = OnlyLikesSingleDigits(List(4, 5))

answered Oct 1, 2014 at 7:07

hellraiser

1,45112 silver badges19 bronze badges

Collectives™ on Stack Overflow

Initialization of class members using constructor parameters

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related