如何在课堂外重新定义类的功能

class Function
{
public:
    std::string Name;
    void call(std::string x);

    Function(std::string Nam)
    {
        Name = Nam;
    }
};

std::vector<Function> funcs;

void Load_FuncLib()
{
    Function print("print");
    Function add("add");

    print.call(std::string x)
    {
        std::cout<< x <<"\n";
    }
    add.call(std::string x)
    {
        std::cout<< std::stoi(x) + std::stoi(x) << "\n";
    }

    funcs.push_back(print);
    funcs.push_back(add);

    funcs.at(0).call("Hello world");
}
class Function
{
public:
    std::string Name;