Scala trait code#

Scala classes can also extend and mix in multiple traits. You can use them just like a Java interface, and you can also use them like abstract classes that have real methods. So no, in the absence of other information, I'd suggest using an abstract class (ideally a sealed one) and two concrete classes that provide implementations. Scala traits are a great feature of the language. If you decide you actually really do want the power provided by traits, they'll still be there, but that'll be a decision you make, not something you just slip into. At least a couple of the other issues might get fixed in future versions of Scala, but it will remain the case that defaulting to classes will constrain your programs in ways that are (at least arguably) consistent with good design. The last reason is by far the most important in my view.

Scala trait code#

Whenever the compiler finds the keyword ‘case’ before ‘class’, it generates a code for us, with some. Case classes have all the properties of normal classes and properties of their own. If you don't need the kind of multiple inheritance they support (and very often you don't), it's better not to have access to it. In this blog, we will look at what are case classes and traits in Scala and how these features support functional programming.

Traits are more powerful, which is bad-in general you want to use the least powerful abstraction that gets the job done.Traits result in more bytecode and some additional overhead related to the use of forwarder methods.Adding a method with an implementation to a trait breaks binary compatibility in a way that adding concrete methods to a class doesn't.Implementing a Scala trait with concrete methods in Java is even more unpleasant. This isn't the case for abstract classes with companion objects, which are implemented on the JVM as a single class with static and instance methods. If you have a trait with a companion object, calling methods on the companion object from Java requires bizarre MyType$.MODULE$.myMethod syntax. I don't know what your source is for the claim that you should prefer traits over abstract classes in Scala, but there are several reasons not to: