Deciding symbolically which subroutine to call is not a robust implementation. You may be setting yourself (or someone else) up for difficult maintenance issues in the future.

That's because you need to guarantee that $var1 and $var2 are always what you expect. Otherwise, as pointed out by TGI, you die "A horrible death";

If you are able to guarantee $var1 and $var2, you'd be doing a dispatch table. But then, dispatch tables are not that easy to maintain. Who knows, you may require $var3 in the future?

Notice how the keys of the dispatch table can be brought in as arguments for a generic function subby($var1, $var2, ...) that takes both variables as first arguments? The dispatch table is explicitly recreating the pass-arguments-to-subroutine functionality of the language.

If the main reason you're calling subs based on variables is just to refactor code, there's got to be a better way.

If you have time, please consider an alternative implementation. Just my 2 cents.