home | help 
std::source...ion::current(3)  C++ Standard Libary std::source...ion::current(3)

NAME
     std::source_location::current - std::source_location::current

Synopsis
	static consteval source_location current() noexcept;  (since C++20)

	Constructs a new source_location object corresponding to the location of
     the call
	site.

Parameters
	(none)

Return value
	If  current()  is  invoked directly (via a function call that names cur-
     rent()), it
	returns a source_location object with implementation-defined values rep-
     resenting the
	location of the call. The values should be affected by	the  #line  pre-
     processor
	directive  in  the  same  manner  as  the predefined macros __LINE__ and
     __FILE__.

	If current() is used in a default member initializer, the  return  value
     corresponds
	to  the  location of the constructor definition or aggregate initializa-
     tion that
	initializes the data member.

	If current() is used in a default argument, the return value corresponds
     to the
	location of the call to current() at the call site.

	If current() is invoked in any other manner, the return value is unspec-
     ified.

Notes
	std::source_location::current typically requires compiler's built-in im-
     plementation.

Example
     // Run this code

      #include <source_location>
      #include <iostream>

      struct src_rec {
	  std::source_location srcl = std::source_location::current();
	  int dummy = 0;

	  src_rec(std::source_location loc = std::source_location::current()) :
	      srcl(loc)    // values of member refer  to  the  location  of  the
     calling function
	  {}
	  src_rec(int i) : // values of member refer to this location
	      dummy(i)
	  {}
	  src_rec(double)  // values of member refer to this location
	  {}
      };

      std::source_location  src_clone(std::source_location a = std::source_loca-
     tion::current())
      {
	  return a;
      }

      std::source_location src_make()
      {
	  std::source_location b = std::source_location::current();
	  return b;
      }

      int main()
      {
	  src_rec srec0;
	  src_rec srec1(0);
	  src_rec srec2(0.0);
	  auto s0 = std::source_location::current();
	  auto s1 = src_clone(s0);
	  auto s2 = src_clone();
	  auto s3 = src_make();

	  std::cout
	      << srec0.srcl.line() << ' ' << srec0.srcl.function_name() << '\n'
	      << srec1.srcl.line() << ' ' << srec1.srcl.function_name() << '\n'
	      << srec2.srcl.line() << ' ' << srec2.srcl.function_name() << '\n'
	      << s0.line() << ' ' << s0.function_name() << '\n'
	      << s1.line() << ' ' << s1.function_name() << '\n'
	      << s2.line() << ' ' << s2.function_name() << '\n'
	      << s3.line() << ' ' << s3.function_name() << '\n';
      }

Possible output:
      31 int main()
      12 src_rec::src_rec(int)
      15 src_rec::src_rec(double)
      34 int main()
      34 int main()
      36 int main()
      25 std::source_location src_make()

See also
	constructor   constructs a new source_location	with  implementation-de-
     fined values
		      (public member function)
	current       obtains the current stacktrace or its given part
	[static]	(public  static  member  function  of  std::basic_stack-
     trace<Allocator>)

http://cppreference.com 	   2024.06.10	   std::source...ion::current(3)
home | help