Camelman,

Good job on Code Complete. The following is somewhat extracted from there and other sources.

The two criteria for function "goodness" are coupling and cohesion. Cohesion can be thought of as the "internal" make-up of the function - does it do one (or a few small things) well. Coupling is how related one function is to another. The goal is to design/implement functions (or procedures, or methods, or whatever) that have high cohesion and low coupling.

With your second example

func1();
sub func1{
  func2();
}
[download]

We have mediocre cohesion and high coupling. Mediocre cohesion because not only does func1 do "its thing" but also because it has a secondary function of controlling flow. There is a high coupling between func1 and func2 because you need to go through func1 to get to func2. This is not always a bad thing but I think we can avoid it here.

That all being said, there are some functions whose sole purpose is to control the flow. Sometimes they're called dispatch functions and other times traffic controllers. (Which is what suaveant explained)

-derby