Implement Display for Item

This is a more idiomatic way of printing the contents of an object
than reaching into its innards. It is also more 1-1 with the original
C# code, which overrides toString for Item.

rust/src/gildedrose.rs

@@ -1,3 +1,4 @@
+use std::fmt::{self, Display};
 pub struct Item {
     pub name: String,
     pub sell_in: i32,
@@ -14,6 +15,12 @@ impl Item {
     }
 }
 
+impl Display for Item {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}, {}, {}", self.name, self.sell_in, self.quality)
+    }
+}
+
 pub struct GildedRose {
     pub items: Vec<Item>,
 }

rust/src/main.rs

@@ -34,7 +34,7 @@ fn main() {
         println!("-------- day {} --------", i);
         println!("name, sellIn, quality");
         for item in &rose.items {
-            println!("{}, {}, {}", item.name, item.sell_in, item.quality);
+            println!("{}", item);
         }
         println!();
         rose.update_quality();