Update property value of immutable object while maintaining immutability
Let's say we have a case class Item with a few properties
case class Item(name:String, category:String, price:Double)At a certain point in your app's lifecycle you might need to 'update' one of the properties of an instance of this case class. Say, for instance, we need to update the 'price' property. However, the Item object is immutable. Of course you can change that:
case class Item(name:String, description:String, var price:Double)However, this is not very nice imho. Instead, Scala case classes allow us to clone the object and selectively change property values by using the copy method. For example:
val items = List(Item("Apple","Fruit", 1.50),Item("Pear", "Fruit", 2.00))
val items_on_sale = items.map(_.copy(price = 0.50))This makes in very easy to make small transformations to your objects while maintaining immutability
Written by Jeroen Rosenberg
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2 Responses
thank you really helpful :D i'm still in the process of learining scala
Thanks for you help!!
I found another way to do this.
Working with your example:
val items = List(Item("Apple","Fruit", 1.50),Item("Pear", "Fruit", 2.00))
val itemsonsale = items.copy(price = 0.50)
I'm in the process of learning scala too
Regards!!
