stdforwardtests.cpp

#include <iostream>
#include <iomanip>

std::string gimme_a_str(const std::string& s)
{
    return "string(\"" + s + "\")";
}

template<typename T>
void action_a(T& a)
{
    std::cout << "action_a&/*" << a << "*/\n";
}

template<typename T>
void action_a(T&& a)
{
    std::cout << "action_a&&/*" << a << "*/\n";
}

template<typename T>
void action_b(T& a)
{
    std::cout << "begin&\n\t";
    action_a(a);
    std::cout << "end&;\n";
}

template<typename T>
void action_b(T&& a)
{
    std::cout << "begin&&\n\t";
    action_a(a);
    std::cout << "end&&;\n";
}

template<typename T>
void action_f(T& a)
{
    std::cout << "forward&\n\t";
    action_a(std::forward<T>(a));
    std::cout << "drawrof&;\n";
}



template<typename T>
void action_f(T&& a)
{
    std::cout << "forward&&\n\t";
    action_a(std::forward<T>(a));
    std::cout << "drawrof&&;\n";
}



int main()
{
    std::string lv{"L1"};
    auto ttl = [](const std::string& s) {
        std::cout << std::setfill('=')
        << std::setw(70) << (" " + s + "\n");
    }; // stupid pointless "modern C++" exhibitionism

    ttl("lvalue call");
    action_a(lv);

    ttl("rvalue call");
    action_a(gimme_a_str("0"));
    
    ttl("lvalue (no forwarding)");
    action_b(lv);

    ttl("lvalue (forwarding)");
    action_f(lv);

    ttl("rvalue (no forwarding)");
    action_b(gimme_a_str("1"));
    
    ttl("rvalue (forwarding)");
    action_f(gimme_a_str("2"));
    
    return 0;
}