From 67cdcc2e12118becb823e20a40cc2687f2b8425a Mon Sep 17 00:00:00 2001
From: Adam Carpenter <53hornet@gmail.com>
Date: Wed, 27 Mar 2019 15:32:37 -0400
Subject: Started Rust in Action MEAP.

---
 meap/meap-code/ch3/ch3-implementing-display.rs | 49 ++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 meap/meap-code/ch3/ch3-implementing-display.rs

(limited to 'meap/meap-code/ch3/ch3-implementing-display.rs')

diff --git a/meap/meap-code/ch3/ch3-implementing-display.rs b/meap/meap-code/ch3/ch3-implementing-display.rs
new file mode 100644
index 0000000..8537bd9
--- /dev/null
+++ b/meap/meap-code/ch3/ch3-implementing-display.rs
@@ -0,0 +1,49 @@
+#![allow(dead_code)] // <1> Silence warnings related to FileState::Open not being used
+
+use std::fmt;  // <2> Bring the `std::fmt` crate into local scope, allowing us to make use of `fmt::Result`
+use std::fmt::{Display};  // <3> Bring `Display` into local scope, avoiding the need for us to prefix it as `fmt::Display` in our code
+
+#[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> Sneakily, we can make use of `write!` to do the grunt work for us. Strings already implement `Display` themselves, so there's very little left for us to do.
+         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> We can rely on the FileState Display implementation in our own code 
+   }
+}
+
+impl File {
+  fn new(name: &str) -> File {
+    File {
+        name: String::from(name), 
+        data: Vec::new(), 
+        state: FileState::Closed
+    }
+  }
+}
+
+fn main() {
+  let f5 = File::new("f5.txt");
+  //...
+  println!("{:?}", f5); // <1>
+  println!("{}", f5); // <1>
+}
\ No newline at end of file
-- 
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