Daniel Ribeiro Daniel Ribeiro - 2 months ago 26
Scala Question

Mixing multiple traits in Scala

Quick note: Examples from the tutorial Scala for Java Refugees Part 5: Traits and Types.

Suppose I have the traits Student, Worker, Underpaid, and Young.

How could I declare a class (not instance), CollegeStudent, with all these traits?

Note: I am aware of the simplests cases, such as CollegeStudent with one or two Traits:

class CollegeStudent extends Student with Worker

Answer

It is easy, when declaring a class you just use the "with" keyword as often as you want

class CollegeStudent extends Student with Worker with Underpaid with Young

the order of the traits can be important if a trait is changing the behavior of the class, it all depends on traits you are using.

Also if you don't want to have a class which always uses the same traits you can use them later:

class CollegeStudent extends Student
new CollegeStudent with Worker with Underpaid with NotSoYoungAnymore