pereira@sri-unix.UUCP (08/15/83)
/* FILES.PL : Routines for playing with files
UTILITY
Lawrence
Updated: 2 April 81
*/
%%% Compile this module
%%% FILES requires no other modules
:- public check_exists/1,
file_exists/1,
open/1,
open/2,
close/2,
delete/1.
:- mode check_exists(+),
file_exists(+),
open(+),
open(?,+),
close(+,+),
delete(+).
% Check to see if a file exists and provide
% an error message if it doesn't
check_exists(File)
:- file_exists(File),
!.
check_exists(File)
:- ttynl, display('! File: '), display(File),
display(' does not exist.'), ttynl,
fail.
% Succeed if a file exists, otherwise fail
file_exists(File)
:- atom(File),
seeing(Old),
( nofileerrors ; fileerrors, fail ),
see(File),
fileerrors,
seen,
see(Old),
!.
% 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)
delete(File)
:- open(Old,File),
rename(File,[]),
see(Old).