use Tk;
require Tk::Entry;
require Tk::Button;

my $mw = MainWindow->new();

my($var1, $var2) = ('val1', 'val2');

my $entry1 = $mw->Entry(-textvariable=> \$var1)->pack();

my $entry2 = $mw->Entry(-textvariable => $var2)->pack();

my $but = $mw->Button(-text=>'print', -command=> sub{print "$var1, $var2\n"; } )->pack();

MainLoop;

__END__
# Output upon pressing print after changeing both entry widget's:

entry1, val2