using the Modules

[programmer.perl]

Hi everyone,

I wrote a module House.pm and I save it in a directory /home/hamidjon/Perl/Learning/code_examples/myModules

The script of a House.pm is:

package House; # Class
sub new { # Class method called a constructor
  my $class = shift;
  my $ref={ "Owner"=>undef, # Attributes of the object
            "Price"=>undef, # Values will be assigned later
  };
bless($ref, $class);
              # $ref now reference an object in this class
return $ref;  # A reference to the object is returned
}
1;

To use this module I'm adding this line to my program: use lib ("/home/hamidjon/Perl/Learning/code_examples/myModules");

Am I doing right by adding this line? Are there any other (most correct) ways to use? What does mean the code line: unshift(@INC, "directory"), first I used unshift(@INC, ""); method but it didn't work, then I used 'use lib ("directory");' and it worked, is it true? Thank you...

Code of program that uses the House.pm module:

#!/usr/bin/perl -w
use lib ("/home/hamidjon/Perl/Learning/code_examples/myModules");
use House;
my $houseref = House->new();

print "\$houseref in main belongs to class ", ref($houseref), "\n";

[zentara]

See unshift @INC versus use lib

[CountZero]

The documentation of the lib pragma says:

This is a small simple module which simplifies the manipulation of @INC at compile time. It is typically used to add extra directories to perl's search path so that later use or require statements will find modules which are not located on perl's default search path.

It is the recommended way of dealing with modules in a non-standard path.

[Anonymous Monk]

Remove the use lib line you could try the following options:
1) export PERL5LIB="/home/hamidjon/Perl/Learning/code_examples/myModules"
2) perl -I/home/hamidjon/Perl/Learning/code_examples/myModules yourScript.pl
3) perl -V will show you a list of system direcotries where perl will look for modules. Once you module is ready you might want to put them there

[frozenwithjoy]

Just to clarify for programmer.perl, in case it isn't clear to him/her: these need to be done at the command line, not inside the script.

[programmer.perl]

Yes, I didn't know that this line must be written in command line. Instead, I was writting any similar line to my program. Also, now I made it clear for myself the factors like "compile time" and a "run time"...

Thanks, now I configured my module directories, afterall, I'll write at top line of my programs (that uses modules) just this line: 'use Module_name;':

(at command line)
export PERL5LIB="/home/hamidjon/Perl/Learning/code_examples/myModules"

...and I check using 'perl -V':

  Built under linux
  Compiled at Mar 23 2012 17:00:13
  %ENV:
    PERL5LIB="/home/hamidjon/Perl/Learning/code_examples/myModules"
  @INC:
    /home/hamidjon/Perl/Learning/code_examples/myModules
    /etc/perl
    /usr/local/lib/perl/5.14.2
    /usr/local/share/perl/5.14.2
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.14
    /usr/share/perl/5.14
    /usr/local/lib/site_perl

[programmer.perl]

I entered this line in a file called 'profile' (/etc/profile) and I can access modules any time without entering each time the line (export PERL5LIB="/home/hamidjon/Perl/Learning/code_examples/myModules"; export PERL5LIB) after the reopening the command line.

[cavac]

If you unshift @INC, you have to do it in a BEGIN clause before using it.

Here's an example from my darkpan repo: If you normally install your module in @INC (for example as part of a CPAN distribution), but don't want the hassle while debugging, you can do something like this:

use strict;
use warnings;

BEGIN {
    if(defined($ARGV[0]) && $ARGV[0] eq "--debug") {
        print("Development INC activated\n\n");
        unshift @INC, "/home/cavac/src/maplat_prodit/lib"; # my darkpa
+n modules
        unshift @INC, "/home/cavac/src/maplat_framework/lib"; # my ope
+n source modules
    } else {
        print("Development INC deactivated, using default INC paths\n\
+n");
    }
}

use Maplat::Worker;
use Maplat::Worker::ProdIT;