Method operator()

test/function_traits_test.cpp:44–47

struct CcI2SStrct {
    std::string operator()(const std::string& str, int x)
    {
        return CcI2SFree(str, x);
    }
    std::string nonCMemF(const std::string& str, int x)
    {
        return CcI2SFree(str, x);