Higher-Order Perl

CHAPTER 2 DISPATCH TABLES

In Chapter 1, we saw how to make functions more flexible by parametrizing their behaviors in terms of other functions. For example, instead of hardwiring the hanoi() function to print a certain message every time it wanted to move a disk, we had it call a secondary function that was passed in from outside. By supplying an appropriate secondary function, we could make hanoi() print out a list of instructions, or check its own moves, or generate a graphic display, without recoding the basic algorithm. Similarly, we were able to abstract the directory-walking behavior away from the file-size-computing behavior of our total_size() function to get a more useful and generally applicable dir_walk() function that could be used ...