Hello,

I am using HTML::Parser to extract Hyperlinks from a Web Page. I wrote a
Module MyParser wich is based on the above quoted Perl module.

Now I want to ensure, that the Parser finished his work before I query the
links. I have a member function getHyperlinks which returns a hash containing
the links. No big thing:

$p->parse;
my %links = $p->getHyperlinks;

I thougt that the parser may still parse, so I assigned a boolean variable
$isParsing which is set to true by the start_document handler and set to
false by the end_document handler.

sub getHyperlinks {
my $self = shift;
while($isParsing) { }
return %{self->{HYPERLINKS}};
}

Actually the parser seems to be blocking now. What is the best way to ensure
that the parser finished extracting all links without blocking the whole
thing?

Best Regards,

Oliver

>
> sub getHyperlinks {
> my $self = shift;
> while($isParsing) { }
> return %{self->{HYPERLINKS}};
> }

The while loop is empty. Nothing can change the value of $isParsing.

You may want to investigate any of the number of extant link
extracting modules on CPAN.

For that matter, if you want to just fetch a page and return a list
of links, it can be as simple as:

use WWW::Mechanize;
my $mech = WWW::Mechanize->new( autocheck => 1 );
$mech->get( "http://myurl" );
for my $link ( $mech->links ) {
print $link->url, "\n";
}

xoxo,
Andy


--
Andy Lester => andy [at] petdance.com => www.petdance.com => AIM:petdance

Am Dienstag, 25. April 2006 04:58 schrieb Andy Lester:
> > sub getHyperlinks {
> > my $self = shift;
> > while($isParsing) { }
> > return %{self->{HYPERLINKS}};
> > }
>
> The while loop is empty. Nothing can change the value of $isParsing.

That's right! At least not in the while loop.

The value is changed in the start_document_handler (true) and
end_document_handler (false). The loop is just to ensure the parser is not
parsing.

But possibly I got confused, because I was handling with the ithread module
and with locking and semaphores the last days!? :)

...
$p->parse;
my %links = $p->getHyperlinks;
...

Is there a chance that the calling program calls $p->getHyperlinks while the
parser is still parsing the page? Or isn't it that the $p->getHyperlinks is
called after the $p->parse returned (though without a value).

I am sorry if I am confusing someone.

Best Regards,

Oliver

>>> sub getHyperlinks {
>>> my $self = shift;
>>> while($isParsing) { }
>>> return %{self->{HYPERLINKS}};
>>> }
>>
>> The while loop is empty. Nothing can change the value of $isParsing.
>
> That's right! At least not in the while loop.
>

Once you get into that while loop, you can never get out.

--
Andy Lester => andy [at] petdance.com => www.petdance.com => AIM:petdance