Re: PrologScript with SWI 6.5.2

Hello Steve,

Guessing that you have the same issue as I did, here is Jan's response
(this happened on this list some three months ago):

>>>

On 09/02/2013 09:04 AM, Boris Vassilev wrote:
> Hello,
>
> Is this section of the manual still correct:
>
> http://www.swi-prolog.org/pldoc/man?section=plscript
>
> In particular, is it still possible to have a file (hello.pl) like this:
>
> #!/path/to/swipl -q -t main -f
> main :- format('hello world~n'), halt.

That depends on the OS. Various Unix flavours have different ways for
processing the remainder of the line after the executable. Before,
SWI-Prolog tried to compensate for that by reading the file itself and
`fix' the command line arguments. This was very complicated and still
caused surprises. Now, it simply passes whatever the OS does as os_argv.
Next, it identifies the `application' arguments as `argv'.

> which can then be run with
> $ ./hello.pl
> (right now Prolog gives me back the help message when I try this)

Which means you have an OS that doesn't break the argument vector in the
first line.

> Reading the email above I understand that this shouldn't be used / is
> wrong, because of the multiple options passed. However, the email also
> talks about script files, starting with header #! line, but what is it
> for if I can drop the #! header altogether and run:
> $ swipl -q -t main -f hello.pl

Of course you can.  But I guess your users do not like this.  The
most portable way is simply

#!/path/to/swipl
<script>

and do all the rest using directives.  For example:

--- t.pl ---
#!/home/jan/bin/swipl

:- set_prolog_flag(verbose, silent).

:- initialization main.

main :-
        current_prolog_flag(argv, Argv),
        format('Called with ~q~n', [Argv]),
        halt.
--- end of t.pl ---

% ./t.pl hello world
Called with [hello,world]

        Cheers --- Jan

P.s.    Currently, the script must have extension .pl.  That must be
        fixed.
>>>


On Wed, Dec 4, 2013 at 12:49 AM, Steve Prior <[email protected]> wrote:

> I'm trying to move PrologScript code from SWI 6.4.1 to 6.5.2 and though
> I've seen in the changelog that command line handling has changed I'm
> having trouble figuring out what changes to make.  The following code seems
> to do exactly what the current documentation from the SWI website does, but
> it doesn't work:
>
> sprior@ubuntu:~/plindexer$ cat foo
> #!/home/sprior/bin/swipl -q -t main -f
>
> main :-
>         write('hello there\n'),
>         halt.
> sprior@ubuntu:~/plindexer$ ./foo
> produces a SWI Prolog usage message.
>
>
> Can someone clue me in?
>
> Steve
> _______________________________________________
> SWI-Prolog mailing list
> [email protected]
> https://lists.iai.uni-bonn.de/mailman/listinfo.cgi/swi-prolog
>
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