$ cat myscript.pl
#!/usr/bin/perl -w

use strict;
...

use lib('.');
use MyModule;

...

my $thingy = new MyModule ( 'thing2' );

print "yeah!\n" if $thingy->is_thing();
print "boo!\n" unless $thingy->is_thing();

##</code><code>##

$ cat MyModule.pm
package MyModule;

use strict;

my @things = (
        'thing1'           ,
        'thing2'           ,
        'thing3'        ,
);

sub is_thing {
   my $self = shift;
   my $t    = $self->{'thing'};

   return grep /^$t$/, $things; 
}
...
1;

##</code><code>##

#use lib('.');
#use MyModule;

##</code><code>##

$ cat myscript.pl MyModule.pm > newscript.pl
$ ./newscript.pl
$ boo!