Scala中子类的特征中的默认类型类实现

trait Printable[A] {
  def print(value: A): Unit
}

trait DefaultPrintable {
  implicit def defaultPrintable[A]: Printable[A] = new Printable[A] {
    def print(value: A): Unit = println(value.toString)
  }
}

class Person(name: String)

object Person extends DefaultPrintable {
  implicit val printablePerson: Printable[Person] = new Printable[Person] {
    def print(person: Person): Unit = println(s"Person(name=${person.name})")
  }
}

object Main extends App {
  def print[A](value: A)(implicit printable: Printable[A]): Unit = {
    printable.print(value)
  }

  val person = new Person("John Doe")
  print(person) // 输出：Person(name=John Doe)
  
  val number = 42
  print(number) // 输出：42
}