Templated method within variadically templated class [duplicate]

Question

This question already has answers here:

Where and why do I have to put the "template" and "typename" keywords? (8 answers)

Closed 9 years ago.

is there any way implementing this behaviour?

template < typename... Args >
class MyClass
{
public:
    typedef std::tuple < Args... > my_tuple;


    template < int n >
    static int bar () { return -5; };

};

What I need is this - I have variadically templated MyClass that contains method foo which is templated by another type (in my case only integer). Is this even possible? I have found simmilar solution but only for non-variadic class.

But this can't be compiled due to bar.

EDIT: I compile on gcc 4.7.2

One should run the method like this MyClass<int, int>::bar<4>()

Could anyone possibly help me please?

Thanks in advance

EDIT2: full code

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <queue>
#include <set>
#include <vector>
#include <string>
#include <cstring>
#include <algorithm>
#include <stack>
#include <map>

template < typename... Args >
class MyClass
{
public:
    typedef std::tuple < Args... > my_tuple;


    template < int n >
    static int bar () { return -5; };

};

template < class A, int N >
static void foo()
{
    A::bar < N > ();
}


int main() { 

    foo< MyClass<int, int>, 4> ();

    return 0;
}

EDIT3: error

$g++ -Wall -std=c++11 -g -o test.out test.cpp
test.cpp: In function ‘void foo()’:
test.cpp:28:16: error: expected primary-expression before ‘)’ token
test.cpp: In instantiation of ‘void foo() [with A = MyClass<int, int>; int N = 4]’:
test.cpp:34:30:   required from here
test.cpp:28:2: error: invalid operands of types ‘<unresolved overloaded function type>’ and ‘int’ to binary ‘operator<’
make: *** [test] Error 1

Answer 1

The problem is that you're calling a template method from within a template without disambiguating the syntax as a template call (see the duplicate for a great explanation).

You need the template qualifier here:

A::template bar<N>();