Solved

calling package using variable in perl

Posted on 2010-11-22
2
293 Views
Last Modified: 2012-06-27
Hi Expert.

I still new in perl. Hope that you guys can guide me with this. :-)

I try to make a perl program that automatically detect a name and use the config file to load the setting.

I'm finish with the detection program and now stuck at the config file.


I'm getting this error:
"Use of uninitialized value in concatenation (.) or string at one.pl line 13."

Thanks for helping.

Regards,
Adnan


The code as follow.

####### one.pl ############
#!/usr/bin/perl

use strict;
use warnings;


my $max_setting;
my $chassis = "car1";
my $readData = "MAXIMUM_SETTING";

$max_setting = ReadPackage($chassis, $readData);

print "$max_setting\n";


sub ReadPackage{

      my ($package, $function) = @_;
      print "package = $package\n";
      print "fucntion  = $function\n";
      my $dataRead;

      $dataRead = eval " use $package (); ${package}::$function()";

      return $dataRead;
}

#########end of one.pl #############

########## car1.pm ###############
package car1;

$MAXIMUM_SETTING = 100;
$RECOMMENDED_SETTING = 70;
$MINIMUM_SETTING = 20;

1;
############ end of car1.pm #########

0
Comment
Question by:adnan_m
2 Comments
 
LVL 26

Accepted Solution

by:
wilcoxon earned 500 total points
ID: 34193434
You had a couple of issues.  You should always check $@ after calling eval.  You should always use strict and warnings even in modules.

### one.pl ###
#!/usr/bin/perl

use strict;
use warnings;

my $max_setting;
my $chassis = "car1";
my $readData = "MAXIMUM_SETTING";

$max_setting = ReadPackage($chassis, $readData);

print "$max_setting\n";

sub ReadPackage{
      my ($package, $function) = @_;
      print "package = $package\n";
      print "fucntion  = $function\n";
      my $dataRead;
      $dataRead = eval " use $package; \$${package}::$function";
      die "${package}::$function failed with\n\t$@" if $@;
      return $dataRead;
}
### end one.pl ###

### car1.pm ###
package car1;

use strict;
use warnings;

our $MAXIMUM_SETTING = 100;
our $RECOMMENDED_SETTING = 70;
our $MINIMUM_SETTING = 20;

1;
### end car1.pm ###
0
 

Author Comment

by:adnan_m
ID: 34193478
Thanks for your replay. I learn a lot for you. I never put the use warning and strict in module before.
I'll take note from your comment regarding to check $@ after calling eval.

The problem have been solve.

Thanks again.

Adnan

0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Many time we need to work with multiple files all together. If its windows system then we can use some GUI based editor to accomplish our task. But what if you are on putty or have only CLI(Command Line Interface) as an option to  edit your files. I…
Checking the Alert Log in AWS RDS Oracle can be a pain through their user interface.  I made a script to download the Alert Log, look for errors, and email me the trace files.  In this article I'll describe what I did and share my script.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
This is a video describing the growing solar energy use in Utah. This is a topic that greatly interests me and so I decided to produce a video about it.

932 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

14 Experts available now in Live!

Get 1:1 Help Now