6.13 SingletonHolder Class Template Quick Facts

• SingletonHolder's declaration is as follows:

  
  
  template <
  
  
     class T,
  
  
     template <class> class CreationPolicy = CreateUsingNew,
  
  
     template <class> class LifetimePolicy = DefaultLifetime,
  
  
     template <class> class ThreadingModel = SingleThreaded
  
  
  >
  
  
  class SingletonHolder;
  
  
  

• You instantiate SingletonHolder by passing it your class as the first template parameter. You select design variations by combining the other four parameters. Example:

  
  
  class MyClass { ... };
  
  
  typedef Singleton<MyClass, CreateStatic>
  
  
     MySingleClass;
  
  
  

• You must define the default constructor, or you must use a creator other than the stock implementations of the Creator policy.

• The canned implementations of the three policies are described in Table 6.1. You can add your own policy classes as long as you respect the requirements.