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  1. #include <mutex>
  2. #include <iostream>
  3.  
  4.  
  5. class locked_stream
  6. {
  7. 	static std::mutex s_out_mutex;
  8.  
  9. 	std::unique_lock<std::mutex> lock_;
  10. 	std::ostream* stream_; // can't make this reference so we can move
  11.  
  12. public:
  13. 	locked_stream(std::ostream& stream)
  14. 		: lock_(s_out_mutex)
  15. 		, stream_(&stream)
  16.     { }
  17.  
  18. 	locked_stream(locked_stream&& other)
  19. 		: lock_(std::move(other.lock_))
  20. 		, stream_(other.stream_)
  21. 	{
  22. 		other.stream_ = nullptr;
  23. 	}
  24.  
  25.     friend locked_stream&& operator << (locked_stream&& s, std::ostream& (*arg)(std::ostream&))
  26.     {
  27. 		(*s.stream_) << arg;
  28.     	return std::move(s);
  29.     }
  30.  
  31.   	template <typename Arg>
  32.     friend locked_stream&& operator << (locked_stream&& s, Arg&& arg)
  33.     {
  34. 		(*s.stream_) << std::forward<Arg>(arg);
  35.     	return std::move(s);
  36.     }
  37. };
  38.  
  39. std::mutex locked_stream::s_out_mutex{};
  40.  
  41. locked_stream locked_cout()
  42. {
  43. 	return locked_stream(std::cout);
  44. }
  45.  
  46. int main (int argc, char * argv[])
  47. {
  48.  	locked_cout() << "hello world: " << 1 << 3.14 << std::endl;
  49. 	return 0;
  50. }
Success #stdin #stdout 0s 3456KB
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stdin
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Standard input is empty
stdout
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hello world: 13.14
https://ideone.com/HezJBD
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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