在match语句中重用匹配的变量

enum Message {
    Quit,
    Move { x: i32, y: i32 },
    Write(String),
    ChangeColor(i32, i32, i32),
}

fn process_message(msg: Message) {
    match msg {
        Message::Quit => println!("The Quit variant has no data to destructure."),
        Message::Move { x, y } => println!("Move in the x direction {} and in the y direction {}", x, y),
        Message::Write(text) => println!("Text message: {}", text),
        Message::ChangeColor(r, g, b) => println!("Change the color to red {}, green {}, and blue {}", r, g, b),
    }
}

sealed trait Message
case object Quit extends Message
case class Move(x: Int, y: Int) extends Message
case class Write(text: String) extends Message
case class ChangeColor(r: Int, g: Int, b: Int) extends Message

def processMessage(msg: Message): Unit = msg match {
  case Quit => println("Quit")
  case Move(x, y) => println(s"Move to $x, $y")
  case Write(text) => println(s"Write: $text")
  case ChangeColor(r, g, b) => println(s"Change color to $r, $g, $b")
}