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  1. #ifndef SERVICE_FACTORY_H_
  2. #define SERVICE_FACTORY_H_
  3.  
  4. #include <string>
  5. #include <map>
  6. #include <memory>
  7.  
  8. class Service {
  9.   public:  
  10.     virtual void free() = 0;
  11. };
  12.  
  13. typedef Service* (*CreationFunction)(void);
  14.  
  15. class Counter : public Service {
  16.   public:
  17.     static Service* create() { return new Counter(); }
  18.     void free() { delete this; }
  19. };
  20.  
  21. class ServiceFactory {
  22.   public:
  23.     ~ServiceFactory() {
  24.       _registeredServices.clear();
  25.     }
  26.  
  27.     static ServiceFactory* getInstance() {
  28.       static ServiceFactory instance;
  29.       return &instance;
  30.     }
  31.  
  32.     void registerService(const std::string &serviceName, CreationFunction fn) {
  33.       _registeredServices[serviceName] = fn;
  34.     }
  35.  
  36.     Service* createService(const std::string &serviceName) {
  37.       auto it = _registeredServices.find(serviceName);
  38.       if(it != _registeredServices.end())
  39.         return it->second();
  40.       return NULL;
  41.     }
  42.   private:
  43.     ServiceFactory() {
  44.       registerService("COUNTER", &Counter::create);
  45.     }
  46.  
  47.     ServiceFactory(const ServiceFactory&) { /* Nothing implemented yet */ }
  48.  
  49.     ServiceFactory& operator=(const ServiceFactory&) { return *this; }
  50.  
  51.     std::map<std::string, CreationFunction> _registeredServices;
  52. };
  53.  
  54. #endif // SERVICE_FACTORY_H_
  55.  
  56. #include <iostream>
  57.  
  58. int main() {
  59.   Service* counter = ServiceFactory::getInstance()->createService("COUNTER");
  60.   if(counter) {
  61.     std::cout << "Counter was made." << std::endl;
  62.     counter->free();
  63.   } else {
  64.     std::cout << "Counter was not made." << std::endl;
  65.   }
  66.  
  67.   return 0;
  68. }
Success #stdin #stdout 0s 3464KB
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Counter was made.
https://ideone.com/edt0OD
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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