template<typename T>
class Singleton : noncopyable
{
public:
static T& instance()
{
pthread_once(&ponce_, &Singleton::init);
assert(value_ != NULL);
return *value_;
}
private:
Singleton();
~Singleton();
static void init()
{
value_ = new T();
if (!detail::has_no_destroy<T>::value)
{
::atexit(destroy);
}
}
static void destroy()
{
typedef char T_must_be_complete_type[sizeof(T) == 0 ? -1 : 1];
T_must_be_complete_type dummy; (void) dummy;
delete value_;
value_ = NULL;
}
private:
static pthread_once_t ponce_;
static T* value_;
};
template<typename T>
pthread_once_t Singleton<T>::ponce_ = PTHREAD_ONCE_INIT;
template<typename T>
T* Singleton<T>::value_ = NULL;
}