Class 25 Objectives

At the end of today's class you should

KNOW:

That a mutator goes into a memory location and changes its value
That set! changes what named memory (i.e. a variable) refers to (it doesn't change the value of the original memory location)
Local structure changes should use mutators; changes to the whole list should use set!

BE ABLE TO:

Choose when to use set! to solve a problem, vs. when to use a mutator

Sample Exam Question:

Consider our banking example, and the following signature and purpose:

;; add-bonus-for-high-balance: -> void
;; The function adds $100 as a high-investor reward to any account
;; in Citibank with a balance exceeding $10,000
;; EFFECT:  may change the balance of some of the accounts in Citibank

Should you use a mutator to solve this problem, or set!? Could you use either? Defend your answer.