reorganized the directories

projects/closure-example/src/main.rs

@@ -0,0 +1,22 @@
+#[derive(Debug)]
+struct Rectangle {
+    width: u32,
+    height: u32,
+}
+
+fn main() {
+    let mut list = [
+        Rectangle { width: 10, height: 1 },
+        Rectangle { width: 3, height: 5 },
+        Rectangle { width: 7, height: 12 },
+    ];
+
+    let mut sort_operations = vec! [];
+    let value = String::from("按照被调用到的 key");
+
+    list.sort_by_key(|r| {
+        sort_operations.push(&value);
+        r.width
+    });
+    println! ("{:#?}\n{:#?}", list, sort_operations);
+}