How to use a perl module that you have written? - perl

Question

I've just written my first Perl module and am having trouble getting it to work with a script I produced also. Here is the error that the Perl interpreter displays when I attempt to run the script that is using my newly created module.
Error message:
scraper_tools_v1.pm did not return a true value at getYid.pl line 5.
BEGIN failed--compilation aborted at getYid.pl line 5.
scraper_tools_v1.pm is the Perl module which I have written and getYid.pl is the Perl script which attempts to utilize the scraper_tools_v1.pm module.
Here is the code for the scraper_tools_v1.pm file:
#!/usr/bin/perl
package scraper_tools_v1;
use strict;
use warnings;
use WWW::Curl::Easy;
# Note this function expects a single parameter which should be in the form of a URL
sub getWebPage($)
{
# Setting up the Curl parameters
my $curl = WWW::Curl::Easy->new; # create a variable to store the curl object
# A parameter set to 1 tells the library to include the header in the body output.
# This is only relevant for protocols that actually have headers preceding the data (like HTTP).
$curl->setopt(CURLOPT_HEADER, 1);
# Setting the target URL to retrieve with the passed parameter
$curl->setopt(CURLOPT_URL, #_);
# Declaring a variable to store the response from the Curl request
my $response_body = '';
# Creating a file handle for CURL to output to, then redirecting our output to the $response_body variable
open(my $fileb, ">",\$response_body) or die $!;
$curl->setopt(CURLOPT_WRITEDATA, $fileb);
# getting the return code from the header to see if the GET was successful
my $return_code = $curl->perform;
# capturing the response code from the GET request in the HTTP header, i.e... 200, 404, 500, etc...
# 200 is success
my $response_code = $curl->getinfo(CURLINFO_HTTP_CODE);
# if the return code is zero than the request was a success
if ($return_code == 0)
{
# A little debug output to keep you informed
print ("Success ". $response_code.": ".#_."\n");
# return whatever was contained on the web page that we just got using a GET
return $response_body;
}
else
{
print ("Failure ". $response_code.": ".#_."\n");
}
close($fileb); # close the file-handle
}
And here is the getYid.pl script which attempts to use the above module
#!/usr/bin/perl
use strict;
use warnings;
use scraper_tools_v1;
my %cat_links; # Hash that stores categories and their numbers (ID's)
my $web_page = scraper_tools_v1->getWebPage("http://something.com/categoryindex.aspx");
my #lines = split(/\n/, $web_page);
foreach my $line (#lines)
{
chomp($line);
if ($line =~ /<option value=\"{1}(.+)\">(.+)<\/option>/)
{
my $num = $1;
my $desc = $2;
$desc =~ s/\s+&\s+/ & /;
$cat_links{$desc} = $num;
}
}
my #allTargetUrls; # make a new array to store all the links we need to extract listings from
$web_page = ''; # Reset this variable so we can reuse it.
my $totalNumberOfListings = 0;
foreach my $key (keys %cat_links)
{
my $target = "http://something.com/categorydetail.aspx?id=$cat_links{$key}&exact_phrase=0";
$web_page = scraper_tools_v1->getWebPage($target);
#lines = split(/\n/, $web_page);
foreach my $line (#lines)
{
my $pages;
chomp($line);
if ($line =~ /We found (\d) listings for your search\./)
{
my $listingsInCat = $1;
print ("$cat_links{$key}, $listingsInCat");
$totalNumberOfListings += $listingsInCat;
}
if ($line =~ /Page 1 of (\d)/)
{
$pages = $1;
}
for (my $i = 1; $i <= $pages; $i++)
{
#build the target urls
my $pageUrl = "http://something.com/categorydetail.aspx?id=$key&search=&exact_phrase=True&city=&state=&zipcode=&page=$i";
push(#allTargetUrls, $pageUrl);
}
}
print("Total number of listings = ".$totalNumberOfListings);
}
Any help in resolving this issue would greatly be appreciated and please note that I have tested both files independently for interpreter errors and found nothing. Thanks to all for taking a look.

Answer 1

When you write a Perl module, you should always end the file with the line
1;
Perl executes code at the module level when the module is imported. If you don't return a true value (1 is true), then you'll get the error you describe. Essentially, Perl is informing you that the initialisation code in your module didn't succeed.