I want to get some suggest for my code aiming at registering service for reuse

Question

I want to implement a RPC server. We can register some method on it. for example:

server.register("echo", [](){ cout << "hello" << endl; });
server.register("add", [](int a, int b, int &c){ c = a+b; });
server.register("print", [](std::string s){ cout << s << endl; });

To do this, I try to use a map to hold all methods. So a class can be hold any type of functions is needed. Here I use a empty base class, and design a derived templated class to hold actual function object. When i need use the method, I can use dynamic_cast base to certain derived.

Beside, I want to assemable c++ perfect forward.

So I write the code below (now all writed by myself):

#include <functional>
#include <string>
#include <memory>
#include <iostream>
#include <vector>
#include <unordered_map>

using namespace std;

class CallableBase {
public:
    virtual ~CallableBase() {}
};

template <class Func>
class Callable: public CallableBase {
    Func f_;
public:
    Callable(Func func): f_(func) {

    }
    template <class ...Args>
    void execute(Args&& ...args) {
        f_(std::forward<Args>(args)...);
    }
};


unordered_map<string, shared_ptr<CallableBase>> methods_;

template <class ...Args>
void execute(const std::string &name, Args&& ... args) {
    using func_t = std::function<void(Args...)>;
    auto f_ptr = dynamic_cast<Callable<func_t>*>(methods_[name].get());
    f_ptr->execute(std::forward<Args>(args)...);
}


class TestObj {
public:
    // TestObj() { cout << "Default Constructor. " << endl; }
    TestObj() { }
    TestObj(const TestObj &o) { cout << "Copy Constructor. " << endl; }
    TestObj(TestObj &&o) { cout << "Move Constructor. " << endl; }
    ~TestObj() = default;
    void Nap() const { cout << a << endl; }
    int a = 2;
};


int main() {

    methods_["echo"] = std::make_shared<Callable<std::function<void(int s)>>>([](int s){ cout << s << endl; });
    methods_["add"] = std::make_shared<Callable<std::function<void(int,int,int&)>>>([](int a, int b, int& c){ c= a+b; });
    methods_["sub"] = std::make_shared<Callable<std::function<void(int,int,int&)>>>([](int a, int b, int& c){ c= a-b; });
    int outer = 1;
    methods_["modify_outer"] = std::make_shared<Callable<std::function<void(int,int)>>>([&outer](int a, int b){ outer = a+b; });

    execute("modify_outer", 1, 2);
    cout << outer << endl;
    execute("echo", 12);
    int c = 0;
    execute("add", 2, 3, c);
    cout << c << endl;
    execute("sub", 2, 3, c);
    cout << c << endl;

    return 0;
}

However, I find it can only use some build-in type, such as int, float. std::string, or TestObj will lead to zsh: segmentation fault.

I don't know what happened, and how to fixed it。。。。