What are you trying to do with it ?
I'm designing a parser specification which includes Perl callbacks. There are good examples of this in both Parse::RecDescent and Parse::Yapp. Damian, of course, uses his own Text::Balanced in Parse::RecDescent.
Francois Desarmenien codes his own much simpler approach in Parse::Yapp. Perl callbacks are contained in brackets. The Perl code may contain nested brackets, and escaped ones are ignored in counting the nesting. Francois knows this is far from dealing with every possibility in legal Perl 5, but he leaves the others up to the user to fix. Francois suggests inserting a comment with balancing brackets into the Perl callback as one solution.
So I have examples before me of the same problem being solved by two excellent programmers in different ways.