ch3-implementing-display.rs

#![allow(dead_code)]              // <1>

use std::fmt;                     // <2>
use std::fmt::{Display};          // <3>

#[derive(Debug,PartialEq)]
enum FileState {
  Open,
  Closed,
}

#[derive(Debug)]
struct File {
  name: String,
  data: Vec<u8>,
  state: FileState,
}

impl Display for FileState {
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
     match *self {
         FileState::Open => write!(f, "OPEN"),      // <4>
         FileState::Closed => write!(f, "CLOSED"),  // <4>
     }
   }
}

impl Display for File {
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
      write!(f, "<{} ({})>",
	         self.name, self.state)              // <5>
   }
}

impl File {
  fn new(name: &str) -> File {
    File {
        name: String::from(name),
        data: Vec::new(),
        state: FileState::Closed,
    }
  }
}

fn main() {
  let f6 = File::new("f6.txt");
  //...
  println!("{:?}", f6);           // <6>
  println!("{}", f6);             // <7>
}