Private Helpers

Use lexical package data to hide a formatting detail.

private_helpers.pl

use strict;
use warnings;

package TicketLabel;

my $prefix = "ticket";

sub label {
    my ($number) = @_;
    return "$prefix-$number";
}

package main;

my $number = ;
my $label = TicketLabel::label($number);

print "number=$number\n";
print "label=$label\n";

use strict;
use warnings;

package TicketLabel;

my $prefix = "ticket";

sub label {
    my ($number) = @_;
    return "$prefix-$number";
}

package main;

my $number = ;
my $label = TicketLabel::label($number);

print "number=$number\n";
print "label=$label\n";

use strict;
use warnings;

package TicketLabel;

my $prefix = "ticket";

sub label {
    my ($number) = @_;
    return "$prefix-$number";
}

package main;

my $number = ;
my $label = TicketLabel::label($number);

print "number=$number\n";
print "label=$label\n";

private-helpers Lexical variables inside a package can keep helper details away from callers.