Dynamic Subroutines

For the purposes of this chapter, I’m going to label as “dynamic subroutines” anything I don’t explicitly name by typing sub some_name or that doesn’t exist until runtime. Perl is extremely flexible in letting me figure out the code as I go along, and I can even have code that writes code. I’m going to lump a bunch of different subroutine topics in this chapter just because there’s no good home for them apart from each other.

We first showed anonymous subroutines in Learning Perl when we showed user-defined sorting, although we didn’t tell you that they were anonymous subroutines. In Intermediate Perl we used them to create closures, work with map and grep, and a few other things. I’ll pick up where Intermediate Perl left off to show just how powerful they can be. With any of these tricks, not knowing everything ahead of time can be very liberating.