C++：在子类中扩展静态容器/映射成员？

#include <iostream>
#include <map>

class Base {
public:
    static std::map<int, std::string> myMap;
};

std::map<int, std::string> Base::myMap = {
    {1, "apple"},
    {2, "banana"},
    {3, "orange"}
};

class Derived : public Base {
public:
    static void addElement(int key, const std::string& value) {
        myMap[key] = value;
    }

    static std::string getElement(int key) {
        return myMap[key];
    }
};

int main() {
    // 在子类中扩展静态容器/映射成员
    Derived::addElement(4, "grape");

    // 在子类中访问扩展后的静态容器/映射成员
    std::cout << Derived::getElement(4) << std::endl;

    return 0;
}