guideline

Consider using Current_Error and Set_Error for run-time error messages.

with Ada.Text_IO;

...

begin
   Ada.Text_IO.Open (File => Configuration_File,
                     Mode => Ada.Text_IO.In_File,
                     Name => Configuration_File_Name);
exception
   when Ada.Text_IO.Name_Error =>
      Ada.Text_IO.Put_Line (File => Ada.Text_IO.Standard_Error,
                            Item => "Can't open configuration file.");
      ...
end;

rationale

The package Text_IO includes the concept of a current error file. You should report errors to the user through the associated subprograms Current_Error and Set_Error instead of the standard output facilities. In interactive applications, using the Text_IO error facilities increases the portability of your user interface.

notes