Question

Let’s say I have two functions:

void a(int arg1) { ... }
void b(int arg1, arg2) { ... }

And I also have a string with the name of the function I want to call, and an array with all parameters:

string func_name = "b"; // 'a' or 'b'
int args[] = { 1, 2 }; // has either 1 or 2 values

I need to call the function dynamically. Doing it with a function that has no arguments is really easy, I just created a map (string function_name => pointer to function).

Now I also want to pass the arguments, so I want to convert an array to actual arguments, something like this:

auto f = std::bind(b, args); // Doesn't compile, requires 1,2 as arguments

I hope the problem is clear and that it is solvable.

Thanks

Answer 1

Inspired by this answer https://stackoverflow.com/a/1287060/942596 you can achieve what you want using macro’s

#define BUILD0(x) x[0]
#define BUILD1(x) BUILD0(x), x[1]
#define BUILD2(x) BUILD1(x), x[2]
#define BUILD3(x) BUILD2(x), x[3]
#define BUILD(x, i) BUILD##i(x)


void foo(int i) {std::cout << i << std::endl;}
void foo(int i, int j) {std::cout << j << std::endl;}
void foo(int i, int j, int k) {std::cout << k << std::endl;}
void foo(int i, int j, int k, int l) {std::cout << l << std::endl;}

int main() {
    int x[] = {1, 2, 3};
    boost::bind(foo, BUILD(x, 2))();
}

Node: this does not account for this situation of 0 parameters.