Re: How to redirect stdout

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
--------------------------------
alex@safran:~> 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) :
>> alex@safran:~> 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.
>> alex@safran:~>
>>
>> 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 : [email protected]
>> Tél : 04.72.18.65.30, Fax : 04.78.33.16.15
>>
> 
> 

-- 
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