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  1. #include <stdio.h>
  2. #include <vector>
  3. #include <memory>
  4. #include <mutex>
  5.  
  6. template <typename T>
  7. class Singleton : public T {
  8.   private:
  9.   static std::unique_ptr<T> instance;
  10.   static std::mutex mutex;
  11.   Singleton();
  12.  
  13.   Singleton<T>(const Singleton<T>&) = delete;
  14.   Singleton<T>&operator=(const Singleton<T>&) = delete;
  15.  
  16.   public:
  17.   static T& getInstance() {
  18.     {
  19.       std::lock_guard<std::mutex> lock(mutex);
  20.       if (nullptr == instance) {
  21.         instance.reset(new T {});
  22.       }
  23.     }
  24.     return *instance.get();
  25.   }
  26.   static void deleteInstance() {
  27.     instance.reset();
  28.   }
  29.   ~Singleton();
  30. };
  31.  
  32. template<typename T>
  33. std::unique_ptr<T> Singleton<T>::instance { nullptr };
  34.  
  35. template<typename T>
  36. std::mutex Singleton<T>::mutex {};
  37.  
  38. template<typename T>
  39. inline Singleton<T>::Singleton() {}
  40.  
  41. template<typename T>
  42. inline Singleton<T>::~Singleton() {}
  43.  
  44. int main() {
  45.   auto & vec = Singleton<std::vector<int>>::getInstance();
  46.   vec.push_back(1);
  47.   vec.push_back(2);
  48.   vec.push_back(3);
  49.   for (auto v : vec) {
  50.     printf("%d\n", v);
  51.   }
  52.   Singleton<std::vector<int>>::deleteInstance();
  53.   return 0;
  54. }
Success #stdin #stdout 0s 16056KB
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https://ideone.com/JQouRY
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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