一个单例

#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;}