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NeedsInit

NeedsInit implements a custom version of std::make_shared that calls the void init() member function of certain objects after construction is complete.

Types

• class NeedsInit

  Helper type used in the constructor of a class to indicate that the custom version of make_shared should be called.

  namespace bdn {
      class NeedsInit {};
      constexpr static const NeedsInit needsInit;
  }
  

• struct has_init_method

  Helper type to determine if a class has a member function called init() at compile time.

  namespace bdn
  {
      template <typename T> struct has_init_method
      {
      private:
          typedef std::true_type yes;
          typedef std::false_type no;
          template <typename U> static auto test(int) -> decltype(std::declval<U>().init(), yes());
          template <typename> static no test(...);
      public:
          static constexpr bool value = std::is_same<decltype(test<T>(0)), yes>::value;
      };
  }
  

Functions

• std::shared_ptr<T> make_shared(bdn::NeedsInit needsInit = bdn::needsInit)

  Specialized version of std::make_shared<>() that calls init() after construction.

  namespace std
  {
      template <typename T, typename std::enable_if<bdn::has_init_method<T>::value, int>::type = 0>
      std::shared_ptr<T> make_shared(bdn::NeedsInit ni = bdn::needsInit)
      {
          auto t = std::allocate_shared<T, std::allocator<T>>(std::allocator<T>(), ni);
          t->init();
          return t;
      }
  }
  

• std::shared_ptr<T> make_shared(bdn::NeedsInit needsInit, Arguments... arguments)

  Specialized version of std::make_shared<>() that calls init() after construction.

  namespace std
  {
      template <typename T, typename... Arguments>
      std::shared_ptr<T> make_shared(bdn::NeedsInit needsInit, Arguments... arguments)
      {
          auto t = std::allocate_shared<T, std::allocator<T>>(std::allocator<T>(), needsInit, arguments...);
          t->init();
          return t;
      }
  }
  

Source

NeedsInit.h