Generalised std::function (std::any for callable objects) - c++

Question

How can I create a variable of generalised std::function type that can take any callable objects? I can't use variadic templates because it'll create a family of different types, while I need a single type, so that I can take different [&] lambdas to a same array.
I did it with functors (example below) that produce std::function<void()>, but for this I have to create a functor for every set of arguments that my functions use. Now I want to use lambdas to bind arguments, but their type is tricky and I can't get different lambdas to the same array.
I understand that this will be very unsafe.
#include <iostream>
#include <vector>
#include <string>
using ChoiceArray = std::vector<std::function<void()>>;
int GetInt(int restriction);
class MenuFunctor {
private:
std::string output;
ChoiceArray arrayOfFunctions;
public:
MenuFunctor(std::string n_output, ChoiceArray n_arrayOfFunctions)
: output(n_output), arrayOfFunctions(n_arrayOfFunctions)
{ }
void operator()() const {
int selection;
std::cout << output;
selection = GetInt(int(arrayOfFunctions.size()));
arrayOfFunctions[selection]();
}
};
class OperationFunctor {
private:
std::function<void(std::vector<std::string>*)> func;
std::vector<std::string>* container;
public:
OperationFunctor(std::function<void(std::vector<std::string>*)> n_func, std::vector<std::string>* n_container)
: func(n_func), container(n_container)
{ }
void operator()() const {
func(container);
}
};
void Func1(std::vector<std::string>* container);
void Func2(std::vector<std::string>* container);
void Func3(std::vector<std::string>* container);
int main() {
std::vector<std::string> container;
std::vector<std::string>* containerAddress = &container;
OperationFunctor f1(Func1, containerAddress);
OperationFunctor f2(Func2, containerAddress);
OperationFunctor f3(Func3, containerAddress);
ChoiceArray Array = {f1, f2, f3};
MenuFunctor Start("input 0-2\n", Array);
Start(); // Works
return 0;
}
Also, I tried to take std::vector<std::string> container for Func1-Func3 by reference, but it didn't work, so I went with pointers. It has something to do with perfect forwarding?

Answer 1

Just stuff lambdas into std::function<void()>.
using OperationFunctor = std::function<void()>;
using ChoiceArray = std::vector<OperationFunctor>;
int GetInt(int restriction);
class MenuFunctor {
private:
std::string output;
ChoiceArray arrayOfFunctions;
public:
MenuFunctor(std::string n_output, ChoiceArray n_arrayOfFunctions)
: output(n_output), arrayOfFunctions(n_arrayOfFunctions)
{ }
void operator()() const {
int selection;
std::cout << output;
selection = GetInt(int(arrayOfFunctions.size()));
arrayOfFunctions[selection]();
}
};
void Func1(std::vector<std::string>* container);
void Func2(std::vector<std::string>* container);
void Func3(std::vector<std::string>* container);
int main() {
std::vector<std::string> container;
std::vector<std::string>* containerAddress = &container;
OperationFunctor f1([containerAddress]{ Func1(containerAddress) });
OperationFunctor f2([containerAddress]{ Func2(containerAddress) });
OperationFunctor f3([containerAddress]{ Func3(containerAddress) });
ChoiceArray Array = {f1, f2, f3};
MenuFunctor Start("input 0-2\n", Array);
Start(); // Works
return 0;
}