/* FILES : Routines for playing with files

                                                UTILITY
                                                Lawrence
                                                Updated: 11 September 81
*/

        %%%  FILES requires no other modules



                        % Check to see if a file exists and provide
                        %  an error message if it doesn't

check_exists(File)
     :- exists(File),
        !.

check_exists(File)
     :- ttynl, display('! File: '), display(File),
        display(' does not exist.'), ttynl,
        fail.



                        % Open a file, checking that it exists

open(File)
     :- check_exists(File),
        see(File).



                        % Open a file and return current file

open(Old,File)
     :- seeing(Old),
        open(File).



                        % Close file and see old file again

close(File,Old)
     :- close(File),
        see(Old).



                        % Delete a file (note that rename requires that
                        %  the file be open)
                         % ?? Probably doesn't in EMAS Prolog

delete(File)
     :- open(Old,File),
        rename(File,[]),
        see(Old).