why does dispatch! call invoke?

[b...@rodenhaeuser.de]

Hi, 

newbie here, with a question: I am studying the Sinatra code, and there is a piece I don't quite understand. 

The Base#call! method calls invoke, passing { dispatch! }. But then, dispatch! calls invoke again. 

Why is that second call to invoke needed? Couldn't we just call call static!, filter! and route! (i.e., what's in the block for that second invoke) directly? 

Many thanks in advance!

Ben