Implicit and implicit in Scala for implicit transformation and implicit parameters

Rules:

• Available only if marked implicit
• The implicit transformation being inserted must be a single identifier of the current scope or be associated with the source or target type of the implicit transformation
• Only one implicit definition can be inserted at a time
• Display priority. If it can pass type check directly, no implicit conversion will be performed

Implicit conversion

//The example implicitly converts a string to Int
object Demo {
  case class R(width: Int, height: Int)

  implicit def stringToInt(s: String): Int = Integer.valueOf(s)

  def main(args: Array[String]): Unit = {
    println(R("4", 5))
  }
}

object Demo {
    //In the example, Int is implicitly converted to an R class
  case class R(width: Int, height: Int){
    def + (that: R): R ={
      R(this.width + that.width, this.height + that.width)
    }
    def + (that: Int): R = {
      R(that.width + that, that.height + that)
    }
  }

  implicit def intToR(i: Int): R = R(i, i)

  def main(args: Array[String]): Unit = {
    val r = R(2, 4)
    println(r + 1)
    println(1 + r)
  }
}

object Demo {
    //Convert int to an implicit RMaker class
  case class R(width: Int, height: Int){
    def + (that: R): R ={
      R(this.width + that.width, this.height + that.width)
    }
    def + (that: Int): R = {
      R(that.width + that, that.height + that)
    }
  }

  implicit class RMaker(width: Int){
    def x(height:Int) = R(width, height)
  }

  implicit def stringToInt(s: String): Int = Integer.valueOf(s)
  implicit def intToR(i: Int): R = R(i, i)
  def main(args: Array[String]): Unit = {
    val r = R(2, 4)
    println((1 + r) + (1 x 2))
  }
}

Implicit parameter

object Demo {
  case class SplitPrompt(s: String)

  case class R(width: Int, height: Int)(implicit splitPrompt: SplitPrompt){
    override def toString: String = s"${width}${splitPrompt.s}${height}"
  }

  implicit val prompt: SplitPrompt = SplitPrompt("#")

  implicit class RMaker(width: Int){
    def x(height:Int) = R(width, height)
  }

  implicit def stringToInt(s: String): Int = Integer.valueOf(s)
  implicit def intToR(i: Int): R = R(i, i)
  def main(args: Array[String]): Unit = {
    println(R(2, 4))
  }
}

Context is implicit

object Demo {
  case class SplitPrompt(s: String)
  case class R(width: Int, height: Int){
    override def toString: String = s"${width}${implicitly[SplitPrompt].s}${height}"
  }
  implicit val prompt: SplitPrompt = SplitPrompt("#")
  implicit class RMaker(width: Int){
    def x(height:Int) = R(width, height)
  }
  implicit def stringToInt(s: String): Int = Integer.valueOf(s)
  implicit def intToR(i: Int): R = R(i, i)
  def main(args: Array[String]): Unit = {
    println(R(2, 4))
  }
}