我是cpp的初学者，我有一些这样的代码：

#include <iostream>
#include <utility>
#include <map>
#include <unordered_map>

template<typename T,typename EX>
class Attachable
{
    
    static std::unordered_map<T*,Attachable<T,EX>> attachCaches;

    std::unordered_map<std::string,EX> datas;

    Attachable(T* sender):m_attachedObj(sender)
    {
    }

    bool operator==(const Attachable& other)const
    {
        return m_attachedObj == other.m_attachedObj;
    }
public:

    static Attachable<T,EX> attach(T* sender)
    {
        if(attachCaches.find(sender)==attachCaches.end())
        {
            attachCaches.insert(std::make_pair((sender),Attachable<T,EX>(sender)));
        }

        return attachCaches[(sender)];
    }

    void set(std::string key,EX properties)
    {
        datas.insert(key,properties);
    }

    EX get(std::string key)
    {
        return datas.at(key);
    }

private:
    T* m_attachedObj;
};

class Tester
{
public :
    Tester(){}
};

int main()
{
    Tester* a =new Tester();

    Attachable<Tester,std::string>::attach(a).set("test","typeOfInt");

    std::cout<< Attachable<Tester,std::string>::attach(a).get("test");

}

当我尝试编译这段代码时，我将在第952行收到一个错误，在名为emplace(*_First);的函数处

template <class _Iter, class _Sent>
    void _Insert_range_unchecked(_Iter _First, const _Sent _Last) {
        for (; _First != _Last; ++_First) {
            emplace(*_First);
        }
    }

我尝试使用一些基本的指针，如int，但这仍然不起作用：

int* a =new int(4);

    Attachable<int,std::string>::attach(a).set("test","typeOfInt");

    std::cout<< Attachable<int,std::string>::attach(a).get("test");