How to insert std:bind as function pointer into constant map

Question

I'm trying to insert std::bind as function pointer into std::map so that in later stages I can replace std::placeholders::_1 with actual parameters based on the conditions.

Below is the function pointer declaration:

typedef int (*funcptr)(std::string, int *);

And this is how I insert into the map.

const std::map<std::string, std::pair<int, funcptr >> lookup {
  {                                        ------ >function pointer as element to the map
    "aclk",
    {   
      1, std::bind(getParam,NONE,std::placeholders::_1) 
    }    ---------------------------------------------------> this part
  }
};

Full code:

#include <random>
#include <iostream>
#include <memory>
#include <functional>


#define NONE "0"

std::pair<int, int> getParam(std::string, int *){ 
   return std::make_pair(1,9);
} 

typedef std::pair<int,int> (*funcptr)(std::string, int *); 

const std::map<std::string, std::pair<int, funcptr>> lookup {
  {
    "aclk",
    {   
      1, std::bind(getParam,NONE,std::placeholders::_1) 
    }   
  }
};

int main()
{
   auto f = std::get<1>(lookup.second);
   int a[5] = {1,2,3,4,5};
   f(a); 
}

MY Question:

One or other I'm getting struck with the compilation errors with the above approach.

Error I'm facing right now is:

g++ -std=c++0x bind.cpp
try.cpp:14: error: expected initializer before ‘<’ token

line 14 in the code is

try.cpp:14: const std::map<std::string, std::pair<int, funcptr>> lookup {

Answer 1

As was stated in comments, std::bind returns callable object - it is unnamed class which has operator()(args) and it cannot be casted to pointer to function. You need to use std::function as wrapper.

Another issue, string is bound when std::bind is called, so final functor will take only int* , typedef for funcptr may be:

typedef std::function< std::pair<int,int>(int*) > funcptr;