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  1. #include <algorithm>
  2. #include <iostream>
  3. #include <vector>
  4.  
  5. struct Device;
  6. struct DeviceDependant;
  7.  
  8. struct DeviceDependant {
  9. private:
  10. 	Device * device_;
  11. public:
  12. 	DeviceDependant(Device &);
  13. 	DeviceDependant(DeviceDependant const &);
  14. 	DeviceDependant(DeviceDependant &&);
  15. 	~DeviceDependant();
  16.  
  17. 	void onDeviceLost(Device * dev) {
  18. 		std::cout << "DeviceDependant::onDeviceLost() : this = " << (void*)this << ", dev = " << (void*)dev << std::endl;
  19. 	}
  20.  
  21. 	void register_self();
  22. 	void unregister_self();
  23. };
  24.  
  25. struct Device {
  26. private:
  27. 	std::vector<DeviceDependant *> dependants_;
  28. public:
  29. 	Device() = default;
  30. 	~Device() {
  31. 		notify_dependants();
  32. 	}
  33.  
  34. 	void register_dependant(DeviceDependant * dep) {
  35. 		std::cout << "Device::register_dependant() : this = " << (void*)this << ", dep = " << (void*)dep << std::endl;
  36. 		dependants_.push_back(dep);
  37. 	}
  38.  
  39. 	void unregister_dependant(DeviceDependant const * dep) {
  40. 		std::cout << "Device::unregister_dependant() : this = " << (void*)this << ", dep = " << (void*)dep << std::endl;
  41. 		dependants_.erase(
  42. 			std::remove_if(
  43. 				std::begin(dependants_),
  44. 				std::end(dependants_),
  45. 				[&](DeviceDependant const * local) { return (local == dep); }
  46. 			),
  47. 			std::end(dependants_)
  48. 		);
  49. 	}
  50.  
  51. 	void notify_dependants() {
  52. 		for(auto & dep : dependants_) {
  53. 			dep->onDeviceLost(this);
  54. 		}
  55. 	}
  56. };
  57.  
  58. DeviceDependant::DeviceDependant(Device & dev)
  59. : device_(&dev) {
  60. 	register_self();
  61. }
  62.  
  63. DeviceDependant::DeviceDependant(DeviceDependant const & dep)
  64. : device_(dep.device_) {
  65. 	register_self();
  66. }
  67.  
  68. DeviceDependant::DeviceDependant(DeviceDependant && dep)
  69. : device_(nullptr) {
  70. 	dep.unregister_self();
  71. 	std::swap(device_, dep.device_);
  72. 	register_self();
  73. }
  74.  
  75. DeviceDependant::~DeviceDependant() {
  76. 	if(device_) {
  77. 		device_->unregister_dependant(this);
  78. 	}
  79. }
  80.  
  81. void DeviceDependant::register_self() {
  82. 	if(device_) {
  83. 		device_->register_dependant(this);
  84. 	}
  85. }
  86.  
  87. void DeviceDependant::unregister_self() {
  88. 	if(device_) {
  89. 		device_->unregister_dependant(this);
  90. 	}
  91. }
  92.  
  93. int main(int argc, char ** argv) {
  94. 	Device dev;
  95. 	DeviceDependant dep1(dev);
  96. 	DeviceDependant dep2(dev);
  97. 	{
  98. 		DeviceDependant dep3(dev);
  99. 	}
  100. 	DeviceDependant dep4 = std::move(dep2);
  101. 	dev.notify_dependants();
  102.  
  103. 	return 0;
  104. }
Success #stdin #stdout 0s 3032KB
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stdin
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Standard input is empty
stdout
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Device::register_dependant() : this = 0xbfa68f04, dep = 0xbfa68ef8
Device::register_dependant() : this = 0xbfa68f04, dep = 0xbfa68efc
Device::register_dependant() : this = 0xbfa68f04, dep = 0xbfa68f00
Device::unregister_dependant() : this = 0xbfa68f04, dep = 0xbfa68f00
Device::unregister_dependant() : this = 0xbfa68f04, dep = 0xbfa68efc
Device::register_dependant() : this = 0xbfa68f04, dep = 0xbfa68f00
DeviceDependant::onDeviceLost() : this = 0xbfa68ef8, dev = 0xbfa68f04
DeviceDependant::onDeviceLost() : this = 0xbfa68f00, dev = 0xbfa68f04
Device::unregister_dependant() : this = 0xbfa68f04, dep = 0xbfa68f00
Device::unregister_dependant() : this = 0xbfa68f04, dep = 0xbfa68ef8
https://ideone.com/GJIjdH
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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