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std::source_location(3)	      C++ Standard Libary      std::source_location(3)

NAME
       std::source_location - std::source_location

Synopsis
	  Defined in header <source_location>
	  struct source_location;	       (since C++20)

	  The  std::source_location class represents certain information about
       the source code,
	  such as file names, line numbers, and	 function  names.  Previously,
       functions that
	  desire  to obtain this information about the call site (for logging,
       testing,	or
	  debugging purposes) must use macros so that predefined  macros  like
       __LINE__	and
	  __FILE__   are   expanded   in   the	context	 of  the  caller.  The
       std::source_location class
	  provides a better alternative.

	  std::source_location	meets	the   DefaultConstructible,   CopyCon-
       structible,
	  CopyAssignable    and	   Destructible	   requirements.   Lvalue   of
       std::source_location meets
	  the Swappable	requirement.

	  Additionally,	the following conditions are true:

	    * std::is_nothrow_move_constructible_v<std::source_location>,
	    * std::is_nothrow_move_assignable_v<std::source_location>, and
	    * std::is_nothrow_swappable_v<std::source_location>.

	  It is	intended that std::source_location has a small size and	can be
       copied
	  efficiently.

	  It  is  unspecified  whether	the  copy/move	constructors  and  the
       copy/move assignment
	  operators of std::source_location are	trivial	and/or constexpr.

Member functions
		Creation
	  constructor	 constructs a new source_location with implementation-
       defined values
			(public	member function)
	  current	constructs a new source_location corresponding to  the
       location	of the
	  [static]	call site
			(public	static member function)
		Field access
	  line		return the line	number represented by this object
			(public	member function)
	  column	return the column number represented by	this object
			(public	member function)
	  file_name	return the file	name represented by this object
			(public	member function)
	  function_name	 return	 the  name of the function represented by this
       object, if any
			(public	member function)

Notes
	     Feature-test macro	     Value    Std		     Feature
	  __cpp_lib_source_location 201907L  (C++20)  Source-code  information
       capture
						    (std::source_location)

Example
       // Run this code

	#include <iostream>
	#include <source_location>
	#include <string_view>

	void log(const std::string_view	message,
		 const std::source_location location =
		       std::source_location::current())
	{
	    std::clog << "file:	"
		      << location.file_name() << '('
		      << location.line() << ':'
		      << location.column() << ") `"
		      << location.function_name() << "`: "
		      << message << '\n';
	}

	template<typename T>
	void fun(T x)
	{
	    log(x); // line 20
	}

	int main(int, char*[])
	{
	    log("Hello world!"); // line 25
	    fun("Hello C++20!");
	}

Possible output:
	file: main.cpp(25:8) `int main(int, char**)`: Hello world!
	file:  main.cpp(20:8)  `void  fun(T)  [with  T	= const	char*]`: Hello
       C++20!

See also
			   changes the source code's line number and,  option-
       ally, the current
	  #line		   file	name
			   (preprocessing directive)
	  stacktrace_entry representation of an	evaluation in a	stacktrace
	  (C++23)	   (class)

http://cppreference.com		  2024.06.10	       std::source_location(3)

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