There might be a possibility tho, but it's a bit hackish ...

a mysay(@a) or mysay($a) will alias $_[0] to $a_[0] or $a resp. and so on

But $_[0] won't be aliased if there are no parameters.

So if there is an internal way to check this, you've won.

Unfortunately I'm to busy to check for this and I suppose you don't wanna dive into that amount of magic anyway ... :)

update

Sorry, never mind.

This won't help you distinguishing between no parameters and an empty @a.