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  1. #include <iostream>
  2. #include <stdexcept>
  3. using namespace std;
  4.  
  5.  
  6. class BaseHolder
  7. {
  8. public:
  9.   virtual ~BaseHolder(){}
  10.   virtual BaseHolder* clone() const = 0;
  11. };
  12.  
  13. template<typename T>
  14. class HoldData : public BaseHolder
  15. {
  16. public:
  17.   HoldData(const T& t_) : t(t_){}
  18.  
  19.   virtual BaseHolder* clone() const {
  20.     return new HoldData<T>(t);
  21.   }
  22.  
  23.   T getData() {
  24. 	  return t;
  25.   }
  26.  
  27. private:
  28.   T t;
  29. };
  30.  
  31.  
  32. class Variant
  33. {
  34. public:
  35.  
  36.   Variant() : data(0) {}
  37.  
  38.   template<typename T>
  39.   Variant(const T& t) : data(new HoldData<T>(t)){}
  40.  
  41.   Variant(const Variant& other) : data(other.data ? other.data->clone() : 0) {}
  42.   ~Variant(){delete data;}
  43.  
  44.   template<typename T>
  45.   T getData() {
  46. 	  return ((HoldData<T>*)data)->getData();
  47.   }
  48.  
  49. private:
  50.   BaseHolder* data;
  51.  
  52. private:
  53.   Variant& operator=(const Variant& other) { return *this;} // Not allowed
  54. };
  55.  
  56. struct none {};
  57.  
  58. class Container{
  59. public:
  60. 	Container() : m1_(0), m2_(0), m3_(0){}
  61. 	~Container() {
  62. 		if(m1_)
  63. 			delete m1_;
  64. 		if(m2_)
  65. 			delete m1_;
  66. 		if(m3_)
  67. 			delete m1_;
  68. 	}
  69.  
  70. 	none extract() { return none();}
  71.  
  72. 	template<typename T>
  73. 	void insertM1(T obj) {
  74. 		m1_ = new Variant(obj);
  75. 	}
  76.  
  77. 	template<typename T>
  78. 	T extractM1() {
  79. 		if(m1_ != 0)
  80. 			return m1_->getData<T>();
  81. 		else
  82. 			throw std::runtime_error("Element not set");
  83. 	}
  84.  
  85. 	// TODO: implement m2 and m3
  86.  
  87. 	Variant *m1_;
  88. 	Variant *m2_;
  89. 	Variant *m3_;
  90. };
  91.  
  92. int main() {
  93.  
  94. 	Container obj;
  95.  
  96. 	char M1 = 'Z';
  97. 	obj.insertM1(M1);
  98.  
  99. 	char extractedM1 = obj.extractM1<char>();
  100. 	cout << extractedM1;
  101.  
  102. 	return 0;
  103. }
Success #stdin #stdout 0s 3472KB
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Z
https://ideone.com/BaCWSV
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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