First of all I have to say it's a really bad idea to stuff so many use repeatedly into subs.

Your post is neither short nor concise, so please forgive me if I missed the point, but

> I would like to be able to step through that with the debugger

Did you try to set breakpoints or watch conditions?

If not, please try h b , h w and h h to learn more.

See perldebtut and perldebug for more.

HTH :)