std::source_location

The std::source_location predefined macros like __LINE__ and __FILE__ are expanded in the context of the caller. The std::source_location

std::source_location meets the DefaultConstructible, CopyConstructible, CopyAssignable, Destructible and Swappable

Additionally, the following conditions are true:

• std::is_nothrow_move_constructible_v <std:: source_location >
• std::is_nothrow_move_assignable_v <std:: source_location >
• 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

Notes

Example

#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!");
}

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