Coding Conventions

In addition to following the design recipe, we would like you to observe basic style guidelines for your programs. Not observing these very basic guidelines leads to unreadable code.

Layout Conventions

Naming Conventions

In general, we use the following conventions:

Function Names

Variable Names

Other Names

Use Help Functions to Simplify Your Code

Use help functions to clarify your intentions in a piece of code. That messy junk you just wrote in your function must have had some purpose. Turn it into a help function so you can document its purpose, and give it independent tests.

Short is good. Long is bad. Period.

Here are two radically different versions of the same function.

bad good
; ball-after-tick : Ball -> Ball
(define (ball-after-tick b)
    [(and (<= YUP (where b) YLO)
       (or (<= (ball-x b) XWALL
             (+ (ball-x b)
               (ball-dx b)))
         (>= (ball-x b) XWALL
           (+ (ball-x b)
             (ball-dx b)))))
       (- (* 2 XWALL)
         (ball-x (straight b 1.)))
       (ball-y (straight b 1.))
       (- (ball-dx (straight b 1.)))
       (ball-dy (straight b 1.)))]
    [else (straight b 1.)])) 
; ball-after-tick : Ball -> Ball
(define (ball-after-tick b)
   [(would-hit-wall? b) (ball-at-wall-reversed b)]
   [else (ball-after-straight-move b 1.)]))

Both always return the same answer. But which one do you understand immediately? Which programming style makes sense? Which will drive the TA crazy?

Last modified: Tue Nov 3 16:26:36 Eastern Standard Time 2015