Software Development (CSC 321 2016S) : EBoards
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Related Courses: [Rails Tutorial] [CSC 321 2016S @ EdX] [CSC 321 2015S (Davis)] [CSC 321 2015F (Rebelsky)] [CSC 322 2016S (Rebelsky)]
Misc: [SamR] [Glimmer Labs] [CS@Grinnell] [Grinnell] [Issue Tracker]
Overview
On a sheet of paper (supplied), answer the following questions.
Approaches to handling legacy code?
char str[20]
or
if (strcmp(passwd,"hello world) == 0)
). Can be hard to fix.
Not general, and you will probably need it generalized eventually.Other likely problems that may be harder to note
Code that is never executed
x = false; if (x) { ... }
From Field et al., pp. 2-4.
class Movie REGULAR = 0 NEW_RELEASE = 1 CHILDRENS = 2 attr_reader :title attr_accessor :price_code def initialize(title, price_code) @title, @price_code = title, price_code end end class Rental attr_reader :movie, :days_rented def initialize(movie, days_rented) @movie, @days_rented = movie, days_rented end end class Customer attr_reader :name def initialize(name) @name = name @rentals = [] end def add_rental(arg) @rentals << arg end def statement total_amount, frequent_renter_points = 0, 0 result = "Rental Record for #{@name}\n" @rentals.each do |element| this_amount = 0 # determine amounts for each line case element.movie.price_code when Movie::REGULAR this_amount += 2 this_amount += (element.days_rented - 2) * 1.5 if element.days_rented > 2 when Movie::NEW_RELEASE this_amount += element.days_rented * 3 when Movie::CHILDRENS this_amount += 1.5 this_amount += (element.days_rented - 3) * 1.5 if element.days_rented > 3 end # add frequent renter points frequent_renter_points += 1 # add bonus for a two day new release rental if element.movie.price_code == Movie.NEW_RELEASE && element.days_rented > 1 frequent_renter_points += 1 end # show figures for this rental result += "\t" + element.movie.title + "\t" + this_amount.to_s + "\n" total_amount += this_amount end # add footer lines result += "Amount owed is #{total_amount}\n" result += "You earned #{frequent_renter_points} frequent renter points" result end end
We will focus on
case element.movie.price_code when Movie::REGULAR this_amount += 2 this_amount += (element.days_rented - 2) * 1.5 if element.days_rented > 2 when Movie::NEW_RELEASE this_amount += element.days_rented * 3 when Movie::CHILDRENS this_amount += 1.5 this_amount += (element.days_rented - 3) * 1.5 if element.days_rented > 3 end
What smells bad?
Solutions