Quoting from perlobj under 'Method Invocation':

For C++ fans, there's also a syntax using -> notation that
does exactly the same thing.  The parentheses are required
if there are any arguments.
 
$fred = Critter->find("Fred");
$fred->display('Height', 'Weight');

The indirect object syntax should also work without parens:

copy $copy_file "/ref/webmail","/www/$domain";
[download]

But as TheDamian - and many other people - tell us, this brings more pain than joy, so I'd stick with the extra parentheses.

-- Hofmator