use ADDITION ( &test_addition);
test_addition ( $log);
sub test_addition {
    my $log = shift;
    $log -> message ("Inside the subroutine test_addition);
}
In my main program 
print $log ; gives HASH(0x1e2ec5c)
in the subroutine 
print $log ; gives HASH(0x1e2ec5c)