Fix unexpected memory leak for custom vector example

Author: kolobabka

08-exceptions/myvec-demo/controllable.hh

@@ -1,15 +1,17 @@
 #pragma once
 
 #include <iostream>
+#include <memory>
 #include <stdexcept>
 #include <utility>
 
-struct Controllable {
+struct Controllable final {
   static int control;
-  int *resource_;
+  std::unique_ptr<int> resource_;
   Controllable() : resource_(new int(42)) {}
 
-  Controllable(Controllable &&rhs) noexcept : resource_(rhs.resource_) {
+  Controllable(Controllable &&rhs) noexcept
+      : resource_(std::move(rhs.resource_)) {
     rhs.resource_ = nullptr;
   }
   Controllable &operator=(Controllable &&rhs) noexcept {
@@ -30,5 +32,5 @@ struct Controllable {
     return *this;
   }
 
-  ~Controllable() { delete resource_; }
+  ~Controllable() = default;
 };