How do you create a Perl module?

Question

How do you write a module for Perl? In Python you can use:

# module.py
def helloworld(name):
    print \"Hello, %s\" % name

# main.py
import module
module.         


        

Answer 1

The most traditional way of setting up a module is as follows:

package Foo::Bar;
our @ISA       = qw(Exporter);       # Tells perl what to do with...
our @EXPORT    = qw(sub1 sub2 sub3); # automatically exported subs
our @EXPORT_OK = qw(sub4 sub5);      # exported only when demanded

# code for subs, constants, package variables here

1;  # Doesn't actually have to be 1, just a 'true' value.

and as others have said, you can use it like so:

use Foo::Bar;

Answer 2

A class:

# lib/Class.pm
package Class;
use Moose;

# define the class

1;

A module that exports functions:

# lib/A/Module.pm
package A::Module;
use strict;
use warnings;
use Sub::Exporter -setup => {
    exports => [ qw/foo bar/ ],
};

sub foo { ... }
sub bar { ... }

1;

A script that uses these:

# bin/script.pl
#!/usr/bin/env perl

use strict;
use warnings;

use FindBin qw($Bin);
use lib "$Bin/../lib";

use Class;
use A::Module qw(foo bar);


print Class->new;
print foo(), bar();