Re: maybe a bug with prolog script

Dear Jan,

Thanks a lot for your clear an complete answer.

Cheers

Dominique

Le 11/12/2013 10:40, Jan Wielemaker a écrit :
> On 12/11/2013 12:30 AM, db wrote:
>> Hello,
>>
>> The following prolog script
>>
>> -------------------------------
>> #! /usr/bin/swipl  -t main -s
>>
>> main :-
>>          catch(goal, E, (print_message(error, E), fail)),
>>          halt.
>> main :-
>>          halt(1).
>>
>> goal :-
>>          writeln('hello').
>> ------------------------------
>>
>> works with SWI-Prolog version 6.4.1 for x86_64-linux
>>
>> does not work with SWI-Prolog version 6.6.0 for amd64,
>> it displays :
>>
>> swipl: Usage:
>>      1) swipl --help     Display this message (also -h)
>>      2) swipl --version  Display version information (also -v)
>>      3) swipl --arch     Display architecture
>>      ...
>>
>> If I add arguments it works with SWI-Prolog version 6.4.1 for
>> x86_64-linux
>> and does not with  SWI-Prolog version 6.6.0 for amd64.
>>
>> Why ?
>
> Unix(-like) systems vary in how they handle text after the
> #!/path/to/exe. The old system tried to compensate for that my checking
> the first line, re-reading it and re-interpreting it in a consistent
> manner. This is hard to do in a compatible way and unexpectely forces
> interpretation of the flags when calling "swipl -s script" because you
> do not know whether "swipl -s script" was called or ./script. Anyway, in
> the past this was needed because the stack options needed to be
> processed before Prolog was started. Now we can set everything using
> directives.
>
> Systems do pass the options consistently (AFAIK) if there is a single
> argument.  This allows for --traditional for V7 users who like to stick
> with the old mode :-)
>
> Typically you do something like this:
>
> #!/usr/bin/swipl
>
> :- set_prolog_flag(verbose, silent).
> :- initialization main.
>
> main :-
>      current_prolog_flag(argv, Argv),
>      <process>.
>
> Note that this change also changes the argv flag to return the `user'
> command line options rather than all of them unfiltered.  This is
> easier and compatible to e.g., SICStus and YAP.
>
>      Cheers --- Jan
>
>>
>> I have the same problem with the swi prolog version 6.5.3
>>
>> Thanks a lot for yours answers
>>
>> Dominique
>> _______________________________________________
>> SWI-Prolog mailing list
>> [email protected]
>> https://lists.iai.uni-bonn.de/mailman/listinfo.cgi/swi-prolog
>
> _______________________________________________
> SWI-Prolog mailing list
> [email protected]
> https://lists.iai.uni-bonn.de/mailman/listinfo.cgi/swi-prolog
>
> !DSPAM:152,52a83352222401060812238!
>