Re: How to redirect stdout

[Alexandre Saidi]

Dear Lindsey,
In my question, 'lising' was juste an (unfortunate) example !

I learned however how I'll do  for thisparticular  predicate.

I dont want to boder you so much (specially  Gurvan Le Guernic gave an 
answer that's quite ok, for this task and so forth. Merci beaucoup à 
Gurvan Le Guernic).

However, I tried  the following with no sucess.
Don't worry. things seem much tighter !

I want to thak you for all your answers and post this one :
Is there any way to have documents (other than "taking a deep look" at 
the source of gprolog) to know these low-level predicats ?
Answers would come from there, if any.

cheers.
Merci
--------------------------------
address@hidden:~> gprolog
GNU Prolog 1.2.16
By Daniel Diaz
Copyright (C) 1999-2002 Daniel Diaz
| ?- [user].
compiling user for byte code...
entier(0).
entier(succ(N)) :- entier(N).

user compiled, 3 lines read - 346 bytes written, 5319 ms

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

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

yes
| ?- halt.

ZZZ : I tried with other examples that normaly give 'yes' or 'no' withe 
variables or not.

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

Lindsey Spratt a écrit :
> I did some more investigating...
>
> The particular predicate with which you are testing the redirection of 
> output, listing/0, sends its output to the "top level output", not 
> stdout. So, redirecting stdout doesn't affect the output of listing/0.
>
> Here is an approach that does redirect the output of listing/0, using 
> the internal '$set_top_level_streams'/2 predicate:
>
> ======
> [Lindsey-Spratts-Computer:~/Documents] lindsey% gprolog
> GNU Prolog 1.2.16
> By Daniel Diaz
> Copyright (C) 1999-2002 Daniel Diaz
> | ?- [user].
> compiling user for byte code...
> toto:-true.
> user compiled, 2 lines read - 205 bytes written, 8773 ms
>
> yes
> | ?- open(fichier,write,F), current_input(I), current_output(O), 
> '$set_top_level_streams'(I, F), listing, '$set_top_level_streams'(I, O), 
> close(F).
>
>
> F = '$stream'(2)
> I = '$stream'(0)
> O = '$stream'(1)
>
> yes
> | ?- halt.
> [Lindsey-Spratts-Computer:~/Documents] lindsey% cat fichier
>
> toto.
> [Lindsey-Spratts-Computer:~/Documents] lindsey%
> =====
>
> The redirection using set_output/1 should work when redirecting the 
> output from the 'write/1' predicate.
>
> Cheers,
> Lindsey Spratt
>
> On Mar 1, 2005, at 11:30 AM, Alexandre Saidi wrote:
>
> > Thanks Lindsey,
> > I've been trying any thing I could to make it work.
> > Ther's no way !
> > As I said, I saw a mail in the FAQ saying that stdout is not affected 
> > by set_output.
> > I'm using the version 1.2.16.
> > Perhaps ther'is is a trick withe the interactive mode ?
> >
> > Thanks any way.
> > ---------------------------------------------
> > Here's what I do under prolog (for a test) :
> > address@hidden:~> gprolog
> > GNU Prolog 1.2.16
> > By Daniel Diaz
> > Copyright (C) 1999-2002 Daniel Diaz
> > | ?- [user].
> > compiling user for byte code...
> > toto :- true.
> >
> > user compiled, 2 lines read - 207 bytes written, 4104 ms
> >
> > yes
> > | ?- open(fichier,write,F), current_output(Old), set_output(F), 
> > listing, flush_output(F), flush_output, close(F).
> >
> > toto.
> >
> > F = '$stream'(2)
> > Old = '$stream'(1)
> >
> > (1 ms) yes
> > | ?- halt.
> > address@hidden:~>
> >
> > The file 'fichier' is empty.
> > I've done many other tests with no success.
> > ---------------------------------------------------------
> >
> > Lindsey Spratt a écrit :
> >
> > > Perhaps flush_output(F) before the close(F), or simply 
> > > 'flush_output', would help.
> > > Lindsey
> > > On Mar 1, 2005, at 3:04 AM, Alexandre Saidi wrote:
> > >
> > > > Thanks for your help.
> > > >
> > > > I'd already tried :
> > > >
> > > > | ?-open('/home/alex/fichier',write,F), current_output(Old), 
> > > > set_output(F), a_call, close(F), set_output(Old).
> > > >
> > > > But the file 'fichier' is of size 0 !
> > > >
> > > > So what's wrong with my code?
> > > > should I flush something ?
> > > >
> > > > regards.
> > > >
> > > > AS
> >
> >
> > --
> > Aleksander S. Saidi
> > Ecole Centrale de Lyon
> > Département Mathématiques-Informatique
> > Mél : address@hidden
> > Tél : 04.72.18.65.30, Fax : 04.78.33.16.15

--
Aleksander S. Saidi
Ecole Centrale de Lyon
Département Mathématiques-Informatique
Mél : address@hidden
Tél : 04.72.18.65.30, Fax : 04.78.33.16.15