Can you pass a function so you can later call it? - c++

Question

I want to have objects with one method which calls a function (but every object should have a different function to call). I will try to show you what I mean by showing an example:
class Human
{
public:
void setMyFunction(void func); // specify which function to call
void callMyFunction(); // Call the specified function
};
void Human::setMyFunction(void func) // ''
{
myFunction = func;
}
void Human::callMyFunction() // ''
{
myFunction();
}
void someRandomFunction() // A random function
{
// Some random code
}
int main()
{
Human Lisa; // Create Object
Lisa.setMyFunction(); // Set the function for that object
Lisa.callMyFunction(); // Call the function specified earlier
}
This code (obviously) doesn't work but I hope you understand what I am trying to accomplish.
MfG, TPRammus

Answer 1

You might use std::function.
#include <functional>
class Human
{
std::function<void()> mFunc;
public:
void setMyFunction(std::function<void()> func) { mFunc = func; }
void callMyFunction() { if (mFunc) mFunc(); }
};
Demo

Answer 2

I would suggest using a simple function pointer. Just do this:
class Human
{
public:
using func_t = void (*)();
void setMyFunction(func_t f) {
func = f;
}
void callMyFunction() {
func();
}
private:
func_t func;
};
The reasons why one might prefer function pointers to std::function are:
Performance. Calling std::function tends to be slower, than calling a function by pointer.
std::function needs truly ugly syntax when one needs to bind it to an overloaded function.
Example:
void foo();
void foo(int x = 0);
void check() {
Human h;
h.setMyFunction(&foo);
}
Will fail to compile.