Skip to content

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, Arguments... arguments)

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

    namespace std
    {
        template <typename T, typename... Arguments, typename std::enable_if<bdn::has_init_method<T>::value, int>::type = 0>
        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