The order in which you run things is different. Normally, the module is executed when it is loaded (by use). Now it's executed after your print statements. I wrap my inlined packages with BEGIN, which makes it more like use.

#!/usr/bin/perl -w

use strict;

BEGIN {
   package MyModule;
   ...
}

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

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