导入伴侣对象或扩展特性中哪个更好 [英] Which among importing companion object or extending trait is better

问题描述

我有一个用Spray编写的JSON协议

I have a JSON protocol written in spray

trait MyJsonProtocol {
   //some logic
}

object MyJsonProtocol extends MyJsonProtocol {

}

现在哪个更好?导入此伴侣对象或扩展特征?

Now which is better ?? Importing this companion object or extending the trait ?

推荐答案

如果要创建用于喷雾的JsonFormat实例，则可以直接创建object并import进行创建.这意味着您只有一个隐式val和对象的实例.

If you are creating some JsonFormat instances for spray, then you can just create an object directly and import that. This means that you only have a single instance of your implicit vals and objects.

object MyJsonProtocol extends DefaultJsonProtocol {
  implicit object MyTypeJsonFormat extends RootJsonFormat[MyType] {
    def write(v: MyType): JsValue = ...
    def read(value: JsValue): MyType = ...
  }

  implicit val myClassFormat = jsonFormat5(MyClass)
}

class OtherClass {
  import MyJsonProtocol._

  ...
}

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