Prohibit generating of apply for case class

Question

I\'m writing a type-safe code and want to replace apply() generated for case classes with my own implementation. Here it is:

import shap         


        

Answer 1

If you want to prohibit using some of auto-generated methods of a case class you can define the methods (with proper signature) manually (then they will not be generated) and make them private (or private[this]).

Try

object SomeClass {
  type Aux[TT] = SomeClass { type T = TT }
  def apply[TT <: Data](implicit ev: TT =:!= Data): SomeClass.Aux[TT] = new SomeClass() {type T = TT}
  private def apply(): SomeClass = ??? // added
}

val t: SomeClass = SomeClass() // doesn't compile
val tt: SomeClass.Aux[Remote.type] = SomeClass.apply[Remote.type] //compiles
val ttt: SomeClass.Aux[Data] = SomeClass.apply[Data] //doesn't compile

In principle, the methods (apply, unapply, copy, hashCode, toString) can be generated not by compiler itself but with macro annotations. Then you can choose any subset of them and modify their generation as you want.

Generate apply methods creating a class

how to efficiently/cleanly override a copy method

Also the methods can be generated using Shapeless case classes a la carte. Then you can switch on/off the methods as desired too.

https://github.com/milessabin/shapeless/blob/master/examples/src/main/scala/shapeless/examples/alacarte.scala

https://github.com/milessabin/shapeless/blob/master/core/src/test/scala/shapeless/alacarte.scala