fdas

src/main.rs

@@ -21,62 +21,21 @@ fn bytes_to_utf8() {
     assert_eq!("💖", sparkle_heart);
 }
 
-
-struct Cacher<T> where T: Fn(u32) -> u32 {
-    calculation: T,
-    value: Option<u32>,
-}
-impl<T> Cacher<T> where T: Fn(u32) -> u32 {
-    fn new(calculation: T) -> Cacher<T> {
-        Cacher {
-            calculation,
-            value: None,
-        }
-    }
-    fn value(&mut self, arg: u32) -> u32 {
-        match self.value {
-            Some(v) => v,
-            None => {
-                let v = (self.calculation)(arg);
-                self.value = Some(v);
-                v
-            },
-        }
-    }
-}
-use std::thread;
-use std::time::Duration;
-fn generate_workout(intensity: u32, random_number: u32) {
-    let mut expensive_result = Cacher::new(|num| {
-        println!("calculating slowly...");
-        thread::sleep(Duration::from_secs(2));
-        num
-    });
-    if intensity < 25 {
-        println!(
-            "Today, do {} pushups!",
-            expensive_result.value(intensity)
-        );
-        println!(
-            "Next, do {} situps!",
-            expensive_result.value(intensity)
-        );
-    } else {
-        if random_number == 3 {
-            println!("Take a break today! Remember to stay hydrated!");
-        } else {
-            println!(
-                "Today, run for {} minutes!",
-                expensive_result.value(intensity)
-            );
-        }
-    }
+use std::collections::HashMap;
+fn hmap() {
+    let mut book_reviews = HashMap::new();
+    book_reviews.insert(3, "foo");
+    let key = 3;
+    let x = match book_reviews.get(&key) {
+        Some(value) => value,
+        None => "",
+    };
+    assert_eq!(x, "foo");
 }
-//////////
 
 fn main() {
     get_element_n_of_string();
     misreuse_of_closure();
     bytes_to_utf8();
-    generate_workout(4, 7);
+    hmap();
 }