一個單例

#include <iostream>
#include <string>

using namespace std;

/*
class mm {
private:
  static mm *aa;
public:
  static mm& instance() {
    if (!aa) 
      aa = new mm;
    return *aa;
  }
  void outoup() {
   cout <<"aaaa" <<endl;
  }
};
mm*  mm::aa = 0;
*/
template <typename T>
class Singleton {
private:
  static T *aa;
  static pthread_mutex_t mutex;
public:
  static T& instance() {
    pthread_mutex_lock(&mutex);
    if (!aa) 
      aa = new T;
    pthread_mutex_unlock(&mutex);
    return *aa;
  }

  static void release() {
    pthread_mutex_lock(&mutex);
    if (aa) {
      delete aa; 
      aa = 0;
    }   
    pthread_mutex_unlock(&mutex);
    //pthread_mutex_destroy(&mutex);
  }
};
template <typename T>  T*  Singleton<T>::aa = 0;
template <typename T>   pthread_mutex_t  Singleton<T>::mutex =  PTHREAD_MUTEX_INITIALIZER;

class Test: public Singleton<Test> {
 public:
   void output() {cout << "tset" <<endl;}
};

int main(int argc, char *argv[]) {
  Test::instance().output();

  return 0;
}