模板化多堆栈实现-怎么做? [英] Templated multistack implementation - how?

问题描述

我需要一个"MultiStack"来容纳不同类型的对象，并将每种类型放在单独的堆栈中.

I need a 'MultiStack' taking different types of objects, putting each type in a separate stack.

这是到目前为止的样子.开放的问题是:如何处理多个不同T的容器

This is what it looks like so far. The open problem is: how to handle the containers for a number of different T

class MultiStack
{

public:

    template<typename T>
    const T& Get()
    {
        return Container<T>.back();
    }

    template<typename T>
    void Push( const T& t )
    {
        Container<T>.push_back( t );
    }

    template<typename T>
    void Pop( const T& /*t*/ )
    {
        Container<T>.pop_back();
    }

private:

    // this does not make sense, we obv. need one stack for each T
    // template<typename T>
    // std::vector<T>           Container;

};

现在，我可以使用旧的技巧，将Container置于成员函数中，例如

Now, I could use the old trick, putting the Container in a member function, like

template<typename T>
auto GetContainer()
{
    static std::vector<T> C;
    return C;
}

但是在多线程时代，我不再喜欢这样.是危险"，对！！

but I don't like this anymore in the age of multi-threading. It is 'dangerous', right!?

有没有更好，更优雅的方式?可以想象的是，如果有帮助的话，我会事先知道允许的类型.

Is there a better, elegant way? It is conceivable that I know the allowed types beforehand, if that helps realizing it.

推荐答案

但是在多线程时代，我不再喜欢这样.是危险"，对！！

but I don't like this anymore in the age of multi-threading. It is 'dangerous', right!?

问题不是多线程的.初始化就可以了.不过，您仍然必须像常规的多线程代码一样保护/同步访问.

Issue is not multi-threading. initialization would be fine. You still have to protect/synchronize access though, as regular multi-threading code.

问题是该容器不是每个 MultiTask 实例，因为它是静态的.多数情况下， MultiTask 是一个Singleton.

Issue is that the container is not per instance of MultiTask, as it is static. It is mostly as if MultiTask were a Singleton.

可以想象的是，如果有帮助的话，我会事先知道允许的类型.

It is conceivable that I know the allowed types beforehand, if that helps realizing it.

那有帮助，然后您可以使用 std :: tuple ，类似(C ++ 14):

That helps, you can then use std::tuple, something like (C++14):

template <typename ... Ts>
class MultiStack
{
public:
    template<typename T>
    const T& Get() const
    {
        return GetContainer<T>().back();
    }

    template<typename T>
    void Push(const T& t)
    {
        GetContainer<T>().push_back(t);
    }

    template <typename T>
    void Pop()
    {
        GetContainer<T>().pop_back();
    }

private:
    template <typename T>
    const std::vector<T>& GetContainer() const { return std::get<std::vector<T>>(Containers); }
    template <typename T>
    std::vector<T>& GetContainer() { return std::get<std::vector<T>>(Containers); }

private:
    std::tuple<std::vector<Ts>...> Containers;
};

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