Instantiation Control

Instantiation control allows to specify how the classes which contain the registered operation in answer will be used.

By default, each request will use a single instance, which is destructed after the response is sent. If the contructor takes a long time, because it has to initialize some data, or if one needs to keep information between calls, one should inherit from answer::initialization::Singleton. This will construct the class on load (adapter startup) and will reuse the instance for multiple requests.

class MemoryClass: public answer::instantiation::Singleton{
  std::string _lastCaller;
  public:
    void call(const std::string& name){
      std::cerr << "Hello :" name << std::endl;
      std::cerr << "Previous caller was :" << _lastCaller << std::endl;
      _lastCaller = name;
    }
};

ANSWER_REGISTER_OPERATION(MemoryClass::call);

Another option is answer::initialization::LazySingleton, which will delay calling the contructor until the first request to any of it's member function is required. After initialization the same instance will be used in subsequent requests.