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  1. #include <iostream>
  2. #include <string>
  3. #include <exception>
  4. #include <stdexcept>
  5. using namespace std;
  6.  
  7.  
  8. template<class F> class ScopeGuard
  9. {
  10. private:
  11. 	F f;
  12. 	bool active;
  13. public:
  14. 	ScopeGuard(F f) :f(::std::move(f)), active(true) {}
  15. 	ScopeGuard(ScopeGuard&& rhs) :f(::std::move(rhs.f)), active(rhs.active) { rhs.dismiss();}
  16. 	~ScopeGuard() { if (active) f(); }
  17.  
  18. 	void dismiss() { active = false; }
  19.  
  20. 	ScopeGuard() = delete;
  21. 	ScopeGuard(const ScopeGuard&) = delete;
  22. 	ScopeGuard& operator=(const ScopeGuard&) = delete;
  23. };
  24.  
  25. template<class FF> static ScopeGuard<FF> makeScopeGuard(FF f) { return ScopeGuard<FF>(f); }
  26.  
  27. #define CONCAT_IMPL(s1, s2) s1##s2
  28. #define CONCAT(s1, s2) CONCAT_IMPL(s1, s2)
  29.  
  30. #define SCOPE_GUARD(lambda) \
  31.   auto CONCAT(scope_guard_, __LINE__)(makeScopeGuard(lambda)); \
  32.   (void)CONCAT(scope_guard_, __LINE__);
  33.  
  34.  
  35. void scopeExit(const string& name)
  36. {
  37. 	cout << "Exiting " << name << " scope "
  38. 	     << (uncaught_exception() ? "(there was an exception)" : "(no exception)") << endl;
  39. }
  40.  
  41. int main()
  42. {
  43. 	SCOPE_GUARD([](){ scopeExit("main"); })
  44.  
  45. 	try
  46. 	{
  47. 		SCOPE_GUARD([](){ scopeExit("try"); })
  48. 		throw runtime_error("Spectacular failure!");
  49. 	}
  50. 	catch (const exception& e)
  51. 	{
  52. 		cout << e.what() << endl;
  53. 	}
  54.  
  55. 	return 0;
  56. }
  57.  
Success #stdin #stdout 0s 3232KB
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stdin
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Standard input is empty
stdout
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Exiting try scope (there was an exception)
Spectacular failure!
Exiting main scope (no exception)
https://ideone.com/eDA9tX
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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