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  1. namespace bad
  2. {
  3. 	class Data // always initializes its members, leaves no choice to the client code :(
  4. 	{
  5. 	private:
  6. 	    int   _i;
  7. 	    float _f;
  8. 	    void* _p;
  9.  
  10. 	public:
  11. 	    Data() : _i(0), _f(0.f), _p(nullptr) { }
  12.  
  13. 	    void SetI(int   value) { _i = value; }
  14. 	    void SetF(float value) { _f = value; }
  15. 	    void SetP(void* value) { _p = value; }
  16.  
  17. 	    double GetSomethingMeaningful() const { return !_p ? (_f * _i) : *(double*)_p; }
  18. 	};
  19. }
  20.  
  21. namespace good
  22. {
  23. 	class BasicData // base class for DataSafe and DataFast
  24. 	{
  25. 	protected:
  26. 	    int   _i;
  27. 	    float _f;
  28. 	    void* _p;
  29.  
  30. 	protected:
  31. 	    BasicData() = default; // no initialization, leaves moosor!
  32. 	    BasicData(int i, float f, void* p) : _i(i), _f(f), _p(p) { }
  33.  
  34. 	public:
  35. 	    void SetI(int   value) { _i = value; }
  36. 	    void SetF(float value) { _f = value; }
  37. 	    void SetP(void* value) { _p = value; }
  38.  
  39. 	    double GetSomethingMeaningful() const { return !_p ? (_f * _i) : *(double*)_p; }
  40. 	};
  41.  
  42. 	class DataSafe : public BasicData // always initializes its members
  43. 	{
  44. 	public:
  45. 		DataSafe() : BasicData(0, 0.f, nullptr) { }
  46. 	};
  47.  
  48. 	class DataFast : public BasicData // no implicit members' initialization
  49. 	{
  50. 	};
  51. }
  52.  
  53. #include <iostream>
  54. using std::cout;
  55.  
  56. int main()
  57. {
  58. 	double d = 42.0;
  59. 	void* pd = (void*)&d;
  60.  
  61. 	{
  62. 	    bad::Data obj;
  63. 	    obj.SetI(2);
  64. 	    obj.SetF(3.14);
  65. 	    cout << obj.GetSomethingMeaningful() << '\n';
  66. 	}
  67.  
  68. 	{
  69. 	    good::DataSafe obj;
  70. 	    obj.SetF(3.14);
  71. 	    cout << obj.GetSomethingMeaningful() << '\n';
  72. 	}
  73.  
  74. 	{
  75. 	    good::DataFast obj;
  76. 	    obj.SetP(pd);
  77. 	    cout << obj.GetSomethingMeaningful() << '\n';
  78. 	}
  79. }
  80.  
Success #stdin #stdout 0s 15240KB
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6.28
0
42
https://ideone.com/IynX9F
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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