non-template template parameters for container stream insertion: SFINAE, C++ (clang)

non-template template parameters for container stream insertion: SFINAE

// Can https://stackoverflow.com/a/14311714 be reasonably rewritten with only
// non-template template parameters? (Try 2: SFINAE on the return type works.)

#include <deque>
#include <iostream>
#include <list>
#include <string> // Neither version shown in this file works with std::string.
#include <vector>

#define USE_TEMPLATE_TEMPLATE_PARAMETER_VERSION false

#if USE_TEMPLATE_TEMPLATE_PARAMETER_VERSION
template<typename T, template<class,class...> class C, class... Args>
std::ostream& operator <<(std::ostream& os, const C<T,Args...>& objs)
{
    os << __PRETTY_FUNCTION__ << '\n';
    for (auto const& obj : objs)
        os << obj << ' ';
    return os;
}
#else
template<typename Container>
auto operator <<(std::ostream& os, const Container& objs) -> decltype(os << *objs.begin())
{
    os << __PRETTY_FUNCTION__ << '\n';
    for (auto const& obj : objs)
        os << obj << ' ';
    return os;
}
#endif

int main() // also from SO post, but modified somewhat
{
    std::cout << "Hello, world!" << '\n';
    
    std::vector<float> vf { 1.1, 2.2, 3.3, 4.4 };
    std::cout << vf << '\n';

std::list<char> lc { 'a', 'b', 'c', 'd' };
    std::cout << lc << '\n';

std::deque<int> di { 1, 2, 3, 4 };
    std::cout << di << '\n';

std::string s ("Goodbye!");
    //std::cout << s << '\n'; // doesn't work
}


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