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  1. #include <iostream>
  2. #include <type_traits>
  3.  
  4. template<typename TF>
  5. void write_debug_output( std::ostream & out, TF const& f ) {
  6. 	out << f;
  7. }
  8.  
  9. struct tracer {
  10. 	std::ostream & out;
  11. 	tracer( std::ostream & out, char const * file, int line )
  12. 		: out( out ) {
  13. 		out << file << ":" << line << ": ";
  14. 	}
  15. 	~tracer() {
  16. 		out << std::endl;
  17. 	}
  18.  
  19. 	template<typename TF, typename ... TR>
  20. 	void write( TF const& f, TR const& ... rest ) {
  21. 		write_debug_output( out, f );
  22. 		out << " ";
  23. 		write( rest... );
  24. 	}
  25. 	template<typename TF>
  26. 	void write( TF const& f ) {
  27. 		write_debug_output( out, f );
  28. 	}
  29. 	void write() {
  30. 		//handle the empty params case
  31. 	}
  32. };
  33.  
  34. #define TRACE(...) tracer( std::cout, __FILE__, __LINE__ ).write( __VA_ARGS__ )
  35.  
  36. struct my_object { };
  37. void write_debug_output( std::ostream & out,  my_object const & f ) {
  38. 	out << "**Mine**";
  39. }
  40.  
  41. int main() {
  42.  	my_object a;
  43.  	TRACE( 1, a, "okay" );
  44.  	TRACE( 5.6, my_object() );
  45. }
  46.  
Success #stdin #stdout 0s 3296KB
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stdin
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Standard input is empty
stdout
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prog.cpp:43: 1 **Mine** okay
prog.cpp:44: 5.6 **Mine**
https://ideone.com/Tb6bL2
Bridge between variadic templates and __VA_ARGS__
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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