In some of the earlier versions of the module, you did need to catch triples via the callbacks, but as of 0.10 that is no longer necessary (though it's still possible, and allows you to do some interesting things).

In this case, I think the empty string URI is causing the problem. You need to plug in the URI of the page being parsed here. (If you don't know the URI, you could always put something like 'http://invalid.invalid/'.)

Here's an example usage which should work:

use Data::Dumper;
use LWP::Simple;
use RDF::RDFa::Parser;

my $uri = 'http://www.w3.org/2006/07/SWD/RDFa/testsuite/xhtml1-testcas
+es/0058.xhtml';
my $parser = RDF::RDFa::Parser->new(get($uri), $uri);
$parser->consume;
print Dumper( $parser->graph );
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Right tobyink, adding a uri fixed the problem. Many thanks for responding quickly. More documentation would definitely help, particularly with examples. As you say, adding custom callbacks would allow to do "interesting things" -- some examples would be great. I would be happy to write the documentation up if I knew where to start.

You mention the module is beta, and its version number reflects that. Do you have a roadmap for the module, or are you focusing your energy on Swignition now?

What is the plan for Swignition? Is that going to become a CPAN resident module or will it develop as it is right now, a standalone program? I downloaded it, but it didn't run... it required some dependencies that it couldn't find.

I would definitely like to see RDF::RDFa::Parser develop further and become more robust and a viable alternative to the Python/Ruby/PHP stuff out there. Doesn't matter if it develops as it is, or in a new incarnation as Swignition.

By the way, your Swignition link on your website is broken. The link for 0.15 leads to the older Cognition 0.14 version.

--

when small people start casting long shadows, it is time to go to bed

In any case, the Pod of the module also says

In place of either or both functions you can use the string 'print' which sets the callback to a built-in function which prints the triples to STDOUT as Turtle. Either or both can be set to undef, in which case, no callback is called when a triple is found.

So, that is exactly what I did, but got nothing, nada, zilch.

The relevant code in the module is

if (lc($_[$n]) eq 'print')
            { $this->{'sub'}->[$n] = ($n==0 ? \&_print0 : \&_print1); 
+}

.. a few lines down ..

sub _print0
# Prints a Turtle triple.
{
    my $this    = shift;
    my $element = shift;
    my $subject = shift;
    my $pred    = shift;
    my $object  = shift;
    
    printf("# Triple on element %s.\n", $element->nodePath);
    
    printf("%s %s %s .\n",
        ($subject =~ /^_:/ ? $subject : "<$subject>"),
        "<$pred>",
        ($object =~ /^_:/ ? $object : "<$object>"));
}

.. and so on ..
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