FIVT2020.Spring.UniquePtr

#include <memory>
#include <iostream>

struct A {
  A() { std::cout << "A" << std::endl; }
  ~A() { std::cout << "~A " << b <<  std::endl; }

  int b = 0;
};

template <class T>
class UniquePtr {
public:
  explicit UniquePtr(T* ptr) : ptr_(ptr) {}
  ~UniquePtr() { delete ptr_; }

  // Запрещаем копирование
  UniquePtr(const UniquePtr& other) = delete;
  UniquePtr& operator=(const UniquePtr& other) = delete;

  UniquePtr(UniquePtr&& other) : ptr_(other.ptr_) { other.ptr_ = nullptr; }
  UniquePtr& operator=(UniquePtr&& other) {
    std::swap(ptr_, other.ptr_);
    return *this;
  }

  UniquePtr& operator=(T* other) {
    if(other != ptr_) {
      delete ptr_;
      ptr_ = other;
    }

    return *this;
  }

  T& operator* () { return *ptr_;}
  const T& operator* () const { return *ptr_; }

  T* operator-> () { return ptr_;}
  const T* operator-> () const { return ptr_;}

private:
  T* ptr_ = nullptr;
};

void f(bool throw_exception)
{
//  A a;
  UniquePtr<A> pa(new A());
  (*pa).b = 5;
  pa->b = 6;

  pa = new A();


  if(throw_exception)
    throw std::runtime_error("error");
}

int main() {

  try {
    f(false);
    f(true);
  } catch(const std::exception& exc) {
    std::cout << "g-exception happened: " << exc.what();
  }

  return 0;
}