Re: Use of uninitialized value in subroutine entry at C:/Perl/lib/HTML/TreeBuilder.pm line 108.

[Athanasius]

Hello kanthsri, and welcome to the Monastery!

I re-formatted your code as follows:

#! perl
use Modern::Perl;
use LWP::Simple;
use URI::Escape;
use HTML::TreeBuilder;
use Try::Tiny;

my $look_for = "perl";
my $contents = get "http://www.amazon.com/s/ref=nb_sb_noss?url=search-
+alias%3Dstripbooks&field-keywords=" . uri_escape($look_for);
my $html     = HTML::TreeBuilder->new_from_content($contents);

for my $item ($html->look_down(id => qr/result_\d+/))
{
    # $item->dump;
    # find out structure of HTML
    my $author = try { $item->look_down(class => 'ptBrand')->as_trimme
+d_text };
    print "$author\n";
}

$html->delete;

and ran it with the following result:

16:54 >perl 452_SoPW.pl
by Randal L. Schwartz, brian d foy and Tom Phoenix
by Tom Christiansen, brian d foy, Larry Wall and Jon Orwant Ph.D.
by Tom Christiansen and Nathan Torkington
by Randal L. Schwartz, brian d foy and Tom Phoenix
by Johan Vromans
by Joseph N. Hall, Joshua A. McAdams and brian d foy
by Randal Schwartz, Tom Phoenix and brian d foy
by David N. Blank-Edelman
by brian d foy
by Curtis Poe
by Damian Conway
by Paul E. Hoffman

16:56 >

What output do you get? In what way is the code “not executing” in your system?

Update: Just realised that the title answers my question! What version of HTML::TreeBuilder are you running? Mine is v5.01. What is line 108 in your version of this module?

[kanthsri]

v5.16.1 this is my version of perl and in treebuillder.pm the unitialised value is $new->parse($whunk);

[kanthsri]

this is the version of treebuilder v5.02

[Athanasius]

Line 108 of HTML::TreeBuilder is a call to HTML::TreeBuilder::parse, which (according to lines 1967–8 of the source code) is inherited from HTML::Parser. Parts of that module — including the parse method — are implemented in C, which is compiled for your local machine when you install the module.

So, it seems there are two possibilities:

1. The call to get is failing, as suggested by Anonymous Monk, below. So, the first thing to do is to print out the variable $contents immediately following the call to get but before the call to new_from_content, to verify that get is working correctly.

2. If it is, then check the installation of HTML::Parser on the machine where the code is failing. Perhaps try re-installing this module.

Hope that helps,