This is an excellent application for what is known in computer-science circles as a closure.   Which Perl supports very well.

You can, within a subroutine, define a variable to be a “code reference,” that is to say, to a particular sub that you define on-the-spot and which can refer to local variables or anything else that is “visible” at the particular place where you define that sub.  

Your caller should simply define one of those closures, and pass it in as a parameter to the routine, who simply calls it.   The closure will execute in the context of the code that created it ... that is to say, “your caller.”

“It’s slick to the point of being positively elegant,” and it works.   (May I kindly refer you to a plethora of existing docs here and elsewhere on the Internet for the gory procedural details.)