Simple answer is yes but modules are pretty easy.
You'd prob want more then just one function though to make a module. But if it's just for personal use then something like the following would work:

#!usr/bin/perl -w
use strict;

# Filename 'Linehist.pm' same as package name, Module in same director
+y as the code you wish to call it from

use Tk;

package Linehist;   # Package name (might go before the use Tk I'm nev
+er sure )

sub history {
    my $entry = shift;
    my $cmand = shift; my $hist;
    if ($cmand eq "new") {
        my %hash;
        my @list;
        $hash{hlist} = \@list;
        $hash{place} = 0;
        my $ref = \%hash;
        return $ref;
    } else {$hist = shift;}
    if ($cmand eq "add") {
        my $string = $$entry->get;
        $$entry->delete('0','end');
        push(@{$hist->{hlist}},$string);
        $hist->{place}++;
    } elsif ($cmand eq "up") {
        if ($hist->{place} <= 0) {$hist->{place} = $#{$hist->{hlist}}}
        else {$hist->{place}--};    
        $$entry->delete('0','end');
        $$entry->insert('1',$hist->{hlist}[$hist->{place}]);
    } elsif ($cmand eq "down") {
        $$entry->delete('0','end');
        if ($hist->{place} == $#{$hist->{hlist}}) {
            $hist->{place} = -1;
            return}
        $hist->{place}++;
        $$entry->insert('1',$hist->{hlist}[$hist->{place}]);
    }
}


1;   # Module is loaded by use or require
[download]

Then to call it.

#!usr/bin/perl -w
use stirct;

use Linehist;
my $entry = 'What ever you had';
Linehist->history(\$entry, 'new');
[download]

There are of course alternative ways of calling it. And there's definitely a way of exporting it so you can just call

history(\$entry, 'one');
[download]

come to think of it might be something like this actually

use Linehist qw(history);
[download]

Although something in the modules may have to change to do that.
Hope that helps.

- John