The Stepdown Rule in Clean Code

Question

There is something about the Stepdown Rule (high level function at top and low level next) in clean code (Chapter 3, One Level of Abstraction per Function ).
What should I do when I use coffeescript since there is no function declarations in coffeescript.

example:

 seeAMovie = ()->
     BuyTheTicket()
     watch()

 BuyTheTicket = ()->
     //some thing

 watch = () ->
     //some thing

I want to do like this.

`f = (x) -> ...` counts as a function declaration, doesn't it? And you might want to be a bit more explicit about what this *Stepdown Rule* says. — mu is too short, Aug 16 '13 at 06:42
Stepdown Rule: "We want every function to be followed by those at the next level of abstraction". It mean that we may use a next level function which have not been declared . — user2666750, Aug 16 '13 at 06:52

score 9 · Accepted Answer · edited Jul 20 '16 at 02:07

CoffeeScript doesn't really affect this rule. The rule doesn't have anything to do with declarations, but even if it did, CoffeeScript does have declarations anyway. As @muistooshort said, here's a CoffeeScript function declaration:

functionName = (arg1, arg2) -> 
  functionBodyLine1
  functionBodyLine2

Those parenthesis are optional in the declaration if there are no arguments. Here's an example of the Step-Down Rule in CoffeeScript in action:

highLevel = ->
  doSomethingAlmostAsHighLevel1()
  doSomethingAlmostAsHighLevel2()

doSomethingAlmostAsHighLevel1 = ->
  doSomethingALittleLowerLevel1()

...

Note about your edit: That's perfectly fine and follows the Step-down rule. What is wrong with your sample?

Not mentioned in the book, but Uncle Bob clarified to me that when two functions - at the same level of abstraction - use the same lower level function, they should be ordered like so:

highLevel1 = -> lowLevel()
highLevel2 = -> lowLevel()
lowLevel = -> ...

Ok, I think I have some misunderstanding of this part! Thank you — user2666750, Aug 16 '13 at 07:12

The Stepdown Rule in Clean Code

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