Re: streams

Hi,

Gonna give youthe answer I got some time ago (the same question !).

Things work by the solution (1) but more generaly by (2).

Regards.

Alexandre.

______________________________________________________________

1-

.... Here is what I did (essentially your example but in two steps):

Best regards,
Johannes

$ gprolog
GNU Prolog 1.2.18
By Daniel Diaz
Copyright (C) 1999-2004 Daniel Diaz
| ?- [user].
compiling user for byte code...
entier(0).
entier(succ(N)) :- entier(N).

user compiled, 3 lines read - 348 bytes written, 8476 ms

(1 ms) yes
| ?- open(fichier,write,F), current_input(I), current_output(O),
asserta(streams(F,I,O)),
'$set_top_level_streams'(I, F),entier(succ(succ(0))).
| ?- retract(streams(F,I,O)),
'$set_top_level_streams'(I, O), close(F).

F = '$stream'(2)
I = '$stream'(0)
O = '$stream'(1)

(1 ms) yes
| ?- halt.

$ cat fichier

F = '$stream'(2)
I = '$stream'(0)
O = '$stream'(1)

yes
$

___________________________________________________________

2- via script cpmmand :

Following my question about "stdout redirection in Gprolog", Gurvan Le
Guernic gave a general

answer ("script" command under Unix/Linux) that did the job.

I post it hereby.

This works not only for Gprolog but also for any command.

In order to gather (to mirror) outputs, launch " script -c gprolog
myfile" and "myfile" is a mirrir of the stdout :

(see "man script" also).

Here's an example (sorry for Windoz users !):

---------------------------------------------------------

alex@safran:> script -c gprolog toto

Le script a débuté, le fichier est toto

GNU Prolog 1.2.16

By Daniel Diaz

Copyright (C) 1999-2002 Daniel Diaz

| ?- write(1).

1

yes

| ?- listing.

yes

.......................

| ?- halt.

Script complélé, le fichier est toto

alex@safran:>

alex@safran:> cat toto

Le script a débuté sur mar 01 mar 2005 19:58:00 CET

GNU Prolog 1.2.16

By Daniel Diaz

Copyright (C) 1999-2002 Daniel Diaz

| ?- write(1).

1

yes

| ?- listing.

yes

.....................

| ?- halt.

Script complété sur mar 01 mar 2005 19:58:10 CET

---------------------------------

Cliff Bender a écrit :

Hi,

I'd like some help trying to understand the use of streams. As I
understand, this should produce a file 'out.txt', with the listing in
it. However, the listing gets printed to the screen, and the file is
empty:

| ?- open('out.txt',
write, H, [alias(out)]), current_output(COUT), set_output(out),
listing, set_output(COUT).

squint([], []).
squint([A|B],
[C|D]) :-
integer(A),
C is A * A,
squint(B,
D).
squint([A|B],
[A|C]) :-
squint(B,
C).

COUT = '$stream'(1)
H = '$stream'(2)

(1 ms) yes
| ?-

If anyone has any ideas, suggestions, anything, please reply.

Thanks and have a great weekend.

Cliff

----------

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--
Aleksander S. Saidi
Ecole Centrale de Lyon
Département Mathématiques-Informatique
Mél : [email protected]
Tél : 04.72.18.65.30, Fax : 04.78.33.16.15

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