Add design principle examples

Author: XuhuaHuang

NewHandler/new_handler.cpp

@@ -1,3 +1,4 @@
+// clang-format off
 /*****************************************************************//**
  * \file   new_handler.cpp
  * \brief  settings custom lambda to handle failing new operator calls;
@@ -9,17 +10,18 @@
  * \author Xuhua Huang
  * \date   November 2022
  *********************************************************************/
+// clang-format on
 
 #include <iostream>
 #include <string>
 
 class Widget {
 public:
-    static std::new_handler set_new_handler(std::new_handler p) throw();
-    static void*            operator new(std::size_t size) throw(std::bad_alloc);
+  static std::new_handler set_new_handler(std::new_handler p) throw();
+  static void*            operator new(std::size_t size) throw(std::bad_alloc);
 
 private:
-    static std::new_handler current_handler;
+  static std::new_handler current_handler;
 };
 
 // initialize static member of class Widget
@@ -32,22 +34,22 @@ std::new_handler Widget::current_handler = 0;
  * \return
  */
 std::new_handler Widget::set_new_handler(std::new_handler p) throw() {
-    std::new_handler old_handler = current_handler;
-    current_handler              = p;
-    return old_handler;
+  std::new_handler old_handler = current_handler;
+  current_handler              = p;
+  return old_handler;
 }
 
 class NewHandlerHolder {
 public:
-    explicit NewHandlerHolder(std::new_handler nh)
-        : handler(nh) {}
-    virtual ~NewHandlerHolder() { std::set_new_handler(handler); }
+  explicit NewHandlerHolder(std::new_handler nh)
+    : handler(nh) {}
+  virtual ~NewHandlerHolder() { std::set_new_handler(handler); }
 
 private:
-    std::new_handler handler;
-    // prevent copying
-    NewHandlerHolder(const NewHandlerHolder&)            = delete;
-    NewHandlerHolder& operator=(const NewHandlerHolder&) = delete;
+  std::new_handler handler;
+  // prevent copying
+  NewHandlerHolder(const NewHandlerHolder&)            = delete;
+  NewHandlerHolder& operator=(const NewHandlerHolder&) = delete;
 };
 
 /**
@@ -57,8 +59,8 @@ class NewHandlerHolder {
  * \return
  */
 void* Widget::operator new(std::size_t size) throw(std::bad_alloc) {
-    NewHandlerHolder h(std::set_new_handler(current_handler));
-    return ::operator new(size);
+  NewHandlerHolder h(std::set_new_handler(current_handler));
+  return ::operator new(size);
 } // once the NewHandlerHolder h goes out of scope of this function
 // the global new handler is restored.
 
@@ -68,11 +70,11 @@ void* Widget::operator new(std::size_t size) throw(std::bad_alloc) {
 template <typename T>
 class NewHandlerSupport {
 public:
-    static std::new_handler set_new_handler(std::new_handler p) throw();
-    static void*            operator new(std::size_t size) throw(std::bad_alloc);
+  static std::new_handler set_new_handler(std::new_handler p) throw();
+  static void*            operator new(std::size_t size) throw(std::bad_alloc);
 
 private:
-    static std::new_handler current_handler;
+  static std::new_handler current_handler;
 };
 
 // initialized static private member
@@ -82,16 +84,16 @@ std::new_handler NewHandlerSupport<T>::current_handler = 0;
 // provide set_new_handler function definition
 template <typename T>
 std::new_handler NewHandlerSupport<T>::set_new_handler(std::new_handler p) throw() {
-    std::new_handler old_handler = current_handler;
-    current_handler              = p;
-    return old_handler;
+  std::new_handler old_handler = current_handler;
+  current_handler              = p;
+  return old_handler;
 }
 
 // provide new operator definition
 template <typename T>
 void* NewHandlerSupport<T>::operator new(std::size_t size) throw(std::bad_alloc) {
-    NewHandlerHolder h(std::set_new_handler(current_handler));
-    return ::operator new(size);
+  NewHandlerHolder h(std::set_new_handler(current_handler));
+  return ::operator new(size);
 }
 
 namespace demo {
@@ -101,6 +103,6 @@ class Widget : public NewHandlerSupport<Widget> {};
 } // namespace demo
 
 int main(void) {
-    std::cout << "Hello, world!" << "\n";
-    return EXIT_SUCCESS;
+  std::cout << "Hello, world!" << "\n";
+  return EXIT_SUCCESS;
 }