研究了一下, boost里其实有两种singleton， 还有一种冒似更简单， 精简如下
# pragma once
template <class T>
class boost_singleton
{
private:
__declspec(dllexport) static T & _object;
static void use(T const &) {}
public:
static T & instance() {
static T t;
use(_object);
return t;
}
};
template<class T>
__declspec(dllexport) T & boost_singleton< T >::_object = boost_singleton< T >::instance();
//////////////////////////////////////////////////////////////////////////
//
template <typename T>
class boost_singleton_default
{
private:
struct object_creator
{
object_creator()
{
boost_singleton_default<T>::instance();
}
inline void do_nothing() const {}
};
static object_creator create_object_;
public:
static T &instance()
{
static T obj;
create_object_.do_nothing();
return obj;
}
};
//因为create_object_是类的静态变量，必须有一个通用的声明
template <class T>
typename boost_singleton_default<T>::object_creator boost_singleton_default<T>::create_object_;