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  1. #include <iostream>
  2. #include <vector>
  3. #include <memory>
  4.  
  5. using namespace std;
  6.  
  7. struct BaseComponent
  8. {
  9.     template <typename T>
  10.     T * as()
  11.     {
  12.         return dynamic_cast<T*>(this);
  13.     }
  14.  
  15.     virtual ~BaseComponent() {}
  16. };
  17.  
  18. template <typename T>
  19. struct Component : public BaseComponent
  20. {
  21.     virtual ~Component() {}
  22. };
  23.  
  24. struct PositionComponent : public Component<PositionComponent>
  25. {
  26.     float x, y, z;
  27.  
  28.     virtual ~PositionComponent() {}
  29. };
  30.  
  31. struct AnotherComponent : public Component<AnotherComponent>
  32. {
  33.     virtual ~AnotherComponent () {}
  34. };
  35.  
  36. int main()
  37. {
  38.     std::vector<std::unique_ptr<BaseComponent>> mComponents;
  39.     mComponents.emplace_back(new AnotherComponent);
  40.  
  41.     auto *pos = mComponents[0]->as<PositionComponent>();
  42.     if (pos) {
  43.         pos->x = 1337;
  44.     } else {
  45.         cerr << "Not a PositionComponent." << endl;
  46.     }
  47.  
  48.     return 0;
  49. }
Success #stdin #stdout #stderr 0s 3468KB
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Standard input is empty
stdout
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Standard output is empty
stderr
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Not a PositionComponent.
https://ideone.com/87DMco
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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