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  1. #include <type_traits>
  2. #include <exception>
  3.  
  4. class NonCopyable
  5. {
  6. public:
  7. 	NonCopyable(const NonCopyable&) = delete;
  8. 	NonCopyable(NonCopyable&&) = delete;
  9. 	NonCopyable& operator=(const NonCopyable&) = delete;
  10. 	NonCopyable& operator=(NonCopyable&&) = delete;
  11. 	~NonCopyable() = default;
  12. protected:
  13. 	NonCopyable() = default;
  14. };
  15.  
  16. template <typename T>
  17. class Subsystem : NonCopyable
  18. {
  19. public:
  20. 	template<class ...Args>
  21. 	static bool Create(Args&& ...args)
  22. 	{
  23. 		if( IsValid() )
  24. 			throw ("Trying to create an already created module.");
  25.  
  26. 		instance() = new T(std::forward<Args>(args)...);
  27. 		isCreate() = true;
  28. 		return IsValid();
  29. 	}
  30.  
  31. 	template<typename SubClass, class ...Args>
  32. 	static bool Create(Args&& ...args)
  33. 	{
  34. 		if( IsValid() )
  35. 			throw ("Trying to create an already created module.");
  36.  
  37. 		instance() = static_cast<T*>(new SubClass(std::forward<Args>(args)...));
  38. 		isCreate() = true;
  39. 		return IsValid();
  40. 	}
  41.  
  42. 	static void Destroy()
  43. 	{
  44. 		delete instance();
  45. 		valid() = false;
  46. 		isCreate() = false;
  47. 	}
  48.  
  49. 	static T& Get()
  50. 	{
  51. 		if( !IsValid() )
  52. 			throw ("Trying to access a module but it hasn't been created up yet.");
  53.  
  54. 		return *instance();
  55. 	}
  56.  
  57. 	static const bool IsValid()
  58. 	{
  59. 		return valid() && isCreate();
  60. 	}
  61.  
  62. protected:
  63. 	Subsystem() = default;
  64. 	~Subsystem() = default;
  65.  
  66. 	static T*& instance()
  67. 	{
  68. 		static T* inst = nullptr;
  69. 		return inst;
  70. 	}
  71.  
  72. 	static bool& valid()
  73. 	{
  74. 		static bool inst = false;
  75. 		return inst;
  76. 	}
  77.  
  78. 	static bool& isCreate()
  79. 	{
  80. 		static bool inst = false;
  81. 		return inst;
  82. 	}
  83.  
  84. 	static void setValid(bool bvalid)
  85. 	{
  86. 		valid() = bvalid;
  87. 	}
  88. };
  89.  
  90. template <typename T>
  91. inline T& GetSubsystem()
  92. {
  93. 	return T::Get();
  94. }
  95.  
  96. class Foo1 : public Subsystem<Foo1>
  97. {
  98. public:
  99. 	Foo1(int ni) : i(ni) 
  100. 	{
  101. 		if (i == 0) 
  102. 			return; 
  103. 		setValid(true);
  104. 	}
  105. 	int i;
  106.  
  107. 	void Bar(){i = i + 10;}
  108. };
  109.  
  110. class Foo2 : public Subsystem<Foo2>
  111. {
  112. public:
  113. 	Foo2(int nx, int ny) : x(nx), y(ny) {setValid(true);}
  114. 	int x,y;
  115. };
  116.  
  117. class Foo3 : public Subsystem<Foo3>
  118. {
  119. public:
  120. 	Foo3(float nf) : f(nf) {setValid(true);}
  121. 	float f;
  122. };
  123.  
  124. int main()
  125. {
  126. 	Foo1::Create(10);
  127. 	Foo2::Create(10,20);
  128. 	Foo3::Create(10.4f);
  129.  
  130.  
  131. 	GetSubsystem<Foo1>().Bar();
  132.  
  133.  
  134. 	Foo3::Destroy();
  135. 	Foo2::Destroy();
  136. 	Foo1::Destroy();
  137.  
  138. 	return 0;
  139. }
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https://ideone.com/dTXvd9
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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