instead of prefixing with ampersand, you can force them as a sub call

Actually, prefixing them with an ampersand does force a sub call and, as Jenda pointed out elsewhere in this thread, that isn't always desirable. Using parens, as you suggest, leaves the constants as candidates for inlining. When they are inlined, they aren't sub calls at all, but substituted at compile time with their value. That's a good thing precisely because it saves you that call overhead.

-sauoq
"My two cents aren't worth a dime.";