c++ - 使用可变参数模板创建模板类元组

Question

我正在尝试制作可变参数模板类 postOffice

template <class... AllInputTypes>
class PostOffice {
public:
   PostOffice(AllInputTypes&... akkUboytTypes)
   : allInputMsgStorage(allInputTypes...) {}
...
protected:
   std::tuple<StorageSlot<AllInputTypes>...> allInputMsgStorage; //TODO: Will this work?
}

与 StorageSlot

template<class InputMsgType>
class StorageSlot {
public:
    StorageSlot(InputMsgType& input)
    : readFlag(false),
      writeFlag(false),
      storageField(input)
      //TODO initialize timer with period, get period from CAN
    {}
    virtual ~StorageSlot();
    InputMsgType storageField; //the field that it is being stored into
    bool readFlag; //the flag that checks if it is being read into
    bool writeFlag; //flag that checks if it is being written into
    Timer StorageSlotTimer; //the timer that checks the read and write flag
};

所以在元组中，我试图初始化一个元组

StorageSlot<AllInputType1>, StorageSlot<AllInputType2>,...

等等

这行得通吗？我试过了

std::tuple<StorageSlot<AllInputTypes...>> allInputMsgStorage;

但这会在可变参数模板和单个模板存储槽之间造成不匹配。但是，我不确定如果

std::tuple<StorageSlot<AllInputTypes>...> allInputMsgStorage;

根本没有定义( StorageSlot 不是模板)，更不用说产生正确的结果了。我能想到得到这项工作的唯一原因是拥有 StorageSlot<AllInputTypes>直接发送至postOffice , 做

std::tuple<AllInputTypeStorageSlots...> allInputMsgStorage;

制作PostOffice的模板界面类有点丑

那么这会起作用吗？如果不起作用，我怎样才能让它起作用？

Answer 1

总体概念是正确的——稍加润色，构造函数可以得到完美的转发以提高效率。

此外，StorageSlot 中不需要虚拟析构函数 - 除非您要使用动态多态性，否则始终使用零规则:

可编译代码:

#include <tuple>
#include <string>

struct Timer
{};

template<class InputMsgType>
class StorageSlot {
public:

    template<class ArgType>
    StorageSlot(ArgType&& input)
        : readFlag(false),
        writeFlag(false),
        storageField(std::forward<ArgType>(input))
    //TODO initialize timer with period, get period from CAN
    {}

    InputMsgType storageField; //the field that it is being stored into
    bool readFlag; //the flag that checks if it is being read into
    bool writeFlag; //flag that checks if it is being written into
    Timer StorageSlotTimer; //the timer that checks the read and write flag
};


template <class... AllInputTypes>
class PostOffice {
public:

    //
    // note - perfect forwarding
    //
    template<class...Args>
    PostOffice(Args&&... allInputTypes)
    : allInputMsgStorage(std::forward<Args>(allInputTypes)...)
    {

    }

protected:
    std::tuple<StorageSlot<AllInputTypes>...> allInputMsgStorage; //TODO: Will this work? - yes
};





int main()
{
    PostOffice<int, double, std::string> po(10, 20.1, "foo");

}