Constructor with variable number of arguments-CodePudding

I want to add a constructor that could allow a variable number of arguments. caller is a function that could call other functions with their arguments(something simliar to thread but for calling functions only). I already made it with a function template

template <class C,class ... _Args >
void caller(C(*f) ( _Args ... __args ), _Args ... __args ){(*f ) ( __args ...) ;}

But I need to have a class because it also should make an object of this class. something like this.

caller()

I made a class for caller with a constractor that could call other functions with a known number of arguments.

#include <iostream>
class caller  {
public:
caller(){std::cout<<"Constructor default";  }
caller(void (*Optype)(int),int a){Optype(a);std::cout<<"Constructor 1";  }
//*** Constructor for variable number of arguments**
};

and it works correctly with following code

#include <iostream>
#include "caller"
using namespace std;
void foo(int a){
  cout<<a<<endl;
}
int main()
{
  caller c;
  caller(); 
  caller(foo,2);  
  return 1;
}

I want to know how can I add a constructor which works with different numbers of variables and is it possible it allows different types of variables too? I ask for something like the function template that I already made but in the class.

CodePudding user response：

If you want a variadic list of arguments to the constructor you do this sort of thing:

#include <iostream>

struct Test
{
    template<typename T>
    Test(T i)
    {
        std::cout << "Test(T i) -> i=" << i << std::endl;
    }

    template<typename T, typename... R>
    Test(T i, R... r)
        : Test(r...)
    {
        std::cout << "Test(T i, R... r) -> i=" << i << std::endl;
    }
};

int main()
{
    Test a{1};    
    Test b{"A", 17};
    Test c{18, 2.5f, "B"};

    return 0;
}

CodePudding user response：

Thanks to @Treebeard answer I modified my code as below and it works.

using namespace std;
class thread {
public:
//default constructor
thread(){}
//other constructors
template<class C,typename... R> 
thread(C(*f), R... r){
    (*f ) ( r ...) ; } };


void foo(char a){
  cout<<a<<endl;
}
void foo1(int a,int b , int c){
  cout<<a b c<<endl;
}
int main()
{
  thread t1;
  thread();
  thread(foo,'Z');
  thread(foo1,2,3,100);
  return 1;
}