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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. class Character;
  5. class Human;
  6. class Robot;
  7.  
  8. class Effect {
  9. public:
  10.     virtual void apply(Character *c) { }
  11.     virtual void apply(Human *c) { }
  12.     virtual void apply(Robot *c) { }
  13. };
  14.  
  15. class Character {
  16. public:
  17.     virtual void accept(Effect *effect) = 0;
  18. };
  19.  
  20. class Human : public Character {
  21. public:
  22.     virtual void accept(Effect *effect)
  23.     {
  24.         effect->apply(this);
  25.     }
  26. };
  27.  
  28. class Robot : public Character {
  29. public:
  30.     virtual void accept(Effect *effect)
  31.     {
  32.         effect->apply(this);
  33.     }
  34. };
  35.  
  36. class Fire : public Effect {
  37. public:
  38.     virtual void apply(Human *c) { std::cout << "humans burn" << std::endl; }      
  39. };
  40.  
  41. class Shock : public Effect {
  42. public:
  43.     virtual void apply(Robot *c) { std::cout << "robots get shocked" << std::endl; }      
  44.     virtual void apply(Human *c) { std::cout << "humans get shocked" << std::endl; }      
  45. };
  46.  
  47. class Water : public Effect {
  48. public:
  49.     virtual void apply(Robot *c) { std::cout << "robots don't like water" << std::endl; }      
  50. };
  51.  
  52. int main()
  53. {
  54.     std::vector<Character*> characters;
  55.     characters.push_back(new Robot());
  56.     characters.push_back(new Human());
  57.  
  58.     std::cout << "Fire:" << std::endl;
  59.     Effect *fire = new Fire();
  60.     for(size_t i = 0;i<characters.size();++i)
  61.     {
  62.         characters[i]->accept(fire);
  63.     }
  64.  
  65.     std::cout << "Shock:" << std::endl;
  66.     Effect *shock = new Shock();
  67.     for(size_t i = 0;i<characters.size();++i)
  68.     {
  69.         characters[i]->accept(shock);
  70.     }
  71.  
  72.     std::cout << "Water:" << std::endl;
  73.     Effect *water = new Water();
  74.     for(size_t i = 0;i<characters.size();++i)
  75.     {
  76.         characters[i]->accept(water);
  77.     }
  78.  
  79.  
  80.     // totally leaked some memory
  81. }
Success #stdin #stdout 0.02s 2860KB
comments (?)
stdin 
Standard input is empty
stdout 
Fire:
humans burn
Shock:
robots get shocked
humans get shocked
Water:
robots don't like water
https://ideone.com/hzCPgH
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
public

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