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  1. #include <memory>
  2. #include <unordered_map>
  3.  
  4. class Resource {
  5. public:
  6.     Resource(const std::string&) {}
  7.     virtual ~Resource() {}
  8. };
  9.  
  10. class Texture : public Resource {
  11. public:
  12.     int width;
  13.     int height;
  14.     int channels;
  15.     uint8_t* data;
  16.  
  17.     Texture(const std::string& path) : Resource(path) {
  18.         load(path);
  19.     }
  20.  
  21.     virtual ~Texture() {
  22.         // if needed for whatever reason
  23.         unload();
  24.     }
  25. protected:
  26.     void load(const std::string& path) {
  27.         // loading logic in here
  28.     }
  29.  
  30.     void unload() {
  31.         // unloading logic in here
  32.     }
  33. };
  34.  
  35. class ResourceManager {
  36. public:
  37.     template<typename T>
  38.     std::shared_ptr<T> load(const std::string& path) {
  39.         static_assert(std::is_base_of<Resource, T>::value, "T must inherit from Resource");
  40.  
  41.         auto res = resources[path].lock();
  42.         if(!res) {
  43.             // assuming constructor loads resource
  44.             resources[path] = res = std::make_shared<T>(path);
  45.         }
  46.  
  47.         auto return_value = std::dynamic_pointer_cast<T>(res);
  48.         if(!return_value) {
  49.             throw std::runtime_error(std::string("Resource '") + path + "' is already loaded as another type");
  50.         }
  51.         return return_value;
  52.     }
  53. private:
  54.     std::unordered_map<std::string, std::weak_ptr<Resource>> resources;
  55. };
  56.  
  57. int main() {
  58. 	ResourceManager man;
  59. 	auto tex = man.load<Texture>("path");
  60. }
Success #stdin #stdout 0s 16072KB
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https://ideone.com/n09q6x
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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