Question

There is such function definition:

template<>
template<>
void object::test<1>()
{
}

What does it mean that there are double template<>?

EDIT:

I extracted code which is valid for this example:

#include <iostream>

template <class U>
class A {

    template <int n>
    void test() {

    }
};

template <class T>
class B {
public:
    typedef A<T> object;
};

typedef B<int>::object object;

template<>
template<>
void object::test < 1 > () {
}

int main() {
    return 0;
} 

This code compiles under g++.

Source: TUT test framework

Answer 1

For example,

template<class T = int> // Default T is int
class object<T> {
   template<int R> void test ();
};

Your code:

template<> // T is fixed
template<> // R is fixed
void object<>::test<1>() // T is default int, R is 1
{
}

is equivalent to:

template<> // T is fixed
template<> // R is fixed
void object<int>::test<1>() // T is int, R is 1
{ 
}