Black monkey house: Scala context definition

1, T: M Context Definition

View Definition T <% V requires that there be an implicit conversion from T to V in. Defined in the context of the form T: M, where M is another generic class, it implicitly requires the existence of a value of type M [T] is.
The following class definition requires the existence of a type of implicit value Ordering [T] when you use a method using an implicit value, passing the implicit parameter.

class Pair6[T: Ordering](val first: T, val second: T) {
  def smaller(implicit ord: Ordering[T]) = {
    println(ord)
    if (ord.compare(first, second) < 0) first else second
  }

  override def toString = "(" + first + "," + second + ")"
}

object Main6 extends App{
  override def main(args: Array[String]): Unit = {
    val p6 = new Pair6(1, 2)
    println(p6.smaller)
  }
}

2, simple to understand hermit conversion

object Logger {
  def main(args: Array[String]): Unit = {
    implicit val x:Int = 10
    def play1(implicit x:Int): Unit ={
      println(x)
    }
    play1
  }
}

尖叫提示：调用play1,没有传参数，x进去了，打印10，这句话的意思是，定义了一个play1函数，传一个参数，这个参数是隐士的，可以传，也可以不传，如果你不传的话，它会在play1当前方法所在的作用域里面，去找 有没有和play1参数一样的隐士变量，有的话就可以，当然隐士转换不能出现二义性

Reproduced in: https: //www.jianshu.com/p/63c3e0b6d54c