#include <iostream>
# include <set>
#include <chrono>
#ifndef UNUSED
#define UNUSED(v) (void)(v)
#endif
typedef std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> time_point;
//void logg(const time_point& tp, std::string& name)
void logg(const time_point& tp, const std::string& name)
{
UNUSED(tp);
UNUSED(name);
std::cout << " name: " << name << std::endl;
}
void log_add(const std::string& name, std::multiset<std::string>& names)
{
auto now = std::chrono::system_clock::now();
std::string temp("abc");
logg(now, std::string("xxx"));
logg(now, "xxx");
logg(now, temp);
names.emplace(name);
}
template <typename T>
void log_add_T(T&& name, std::multiset<std::string>& names)
{
auto now = std::chrono::system_clock::now();
logg(now, "xxx");
names.emplace(std::forward<T>(name));
}
int main(int argc, char *argv[])
{
std::multiset<std::string> nameset;
log_add("abcd", nameset);
log_add_T("aaa", nameset);
return 0;
}
1. If logg function of the form void logg (const time_point & tp, std :: string & name), then
logg(now, std::string("xxx"));
logg(now, "xxx");
It will fail to compile.
2. log_add_T function takes a universal reference parameters, use perfect forward, more efficient than log_add!