alias for multi parameter function template

Question

I am trying to create a template for a multi-parameter function, and then an alias for a particular instantiation. From this really good post:

C++11: How to alias a function?

I found example code that works for a single function parameter and single template parameter:

#include <iostream>
namespace Bar
{
   void test()
   {
      std::cout << "Test\n";
   }

   template<typename T>
   void test2(T const& a)
   {
      std::cout << "Test: " << a << std::endl;
   }
}

void (&alias)()        = Bar::test;
void (&a2)(int const&) = Bar::test2<int>;

int main()
{
    Bar::test();
    alias();
    a2(3);
}

When I try to expand to two function parameters as such:

void noBarTest(T const& a, T const& b)
{
    std::cout << "noBarTest: " << a << std::endl;
}

void(&hh)(int const&, int const&) = noBarTest<int, int>;

I get these errors in Visual Studio:

error C2440: 'initializing' : cannot convert from 'void (__cdecl *)(const T &,const T &)' to 'void (__cdecl &)(const int &,const int &)'

IntelliSense: a reference of type "void (&)(const int &, const int &)" (not const-qualified) cannot be initialized with a value of type ""

I thought I followed the pattern exactly in expanding to 2 arguments.
What's the proper syntax for this?

I dont see function noBarTest having template parameters...template <typename T>. — Arunmu
Since this is your first question, I am assuming that you are new to stack overflow. So, Welcome! Use the comment section if you have any difficulty in understanding the solutions offered by others. If you find a working solution, you can accept the answer by clicking on the 'check' button below the counter. That will help you in getting more responses next time when you ask a question. — Arunmu
@Arunmu, Thank you for the welcome. I wasn't sure about when to use comments so now I know. You're right that I left off the template declaration in the code snippet. I had it in there but lost it in editing as I fumbled around trying to format things. — HonestMath

Arunmu Arunmu · Accepted Answer · 2016-05-30T16:51:03

template <typename T>
void noBarTest(T const& a, T const& b)
{
}

void(&hh)(int const&, int const&) = noBarTest<int>; // Only once

int main() {
  return 0;
}

The type parameter int needs to be specified only once in noBarTest<int>.

alias for multi parameter function template

1 Answers