When to use case class or regular class

Question

I have some misunderstanding in what cases I should use case class or regular class following by best practices. I have already read about differences of both classes but cannot imagine myself real-life examples where is reccommended to use case or regular class.

Could anybody show me real examples with explanation why it's reccommended to do so and not otherwise?

Answer 1

If you are going to write purely functional code with immutable objects, you should better try avoid using regular classes. The main idea of the functional paradigm is the separation of data structures and operations on them. Case Classes are a representation of a data structure with the necessary methods. Functions on the data should be described in different software entities (e.g., traits, objects).

Regular classes, on the contrary, link data and operations to provide the mutability. This approach is closer to the object-oriented paradigm.

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As a result, do not use Case Classes if:

1. Your class carries mutable state.
2. Your class includes some logic.
3. Your class is not a data representation and you do not require structural equality.

However, in these cases, you should really think about the style of your code because it probably is not functional enough.

Answer 2

Case Classes are normal classes with syntactic sugar. So there is no real big difference, you can do everything with a case class you can do with a class and vice versa.

Case classes just save you a lot of boiler plate code to write.

Perfect fit, as the name suggests, is the use of case classes in pattern matching with case.

case class MyCase(name: String, age: Int)  data : List[MyCase] = ...  data foreach {      case MyCase(_, age) if age > 21 => println("old enough")     case MyCase("fred", _ ) => println("Got you")     case _ => ... }