Object Oriented

Question 1

class Person
attr_accessor :name, :age
end
p = Person.new
p.name = "Fred"
p.age = 20
puts p.instance_variables

Answer 1

[“@age, @name”]

Question 2

enscapsulation

Answer 2

Encapsulation is the ability for an object to have certain methods and attributes available for 
use publicly (from any section of code), but for others to be visible only withinthe class itself 
or by other objects of the same class.

Question 3

class Person
def anyone_can_access_this; ...; end
def this_is_private; ...; end
def this_is_also_private; ...; end
def another_public_method; ...; end
private :this_is_private, :this_is_also_private
end

Answer 3

enscapsulate methods in one line

Question 4

plymorphism

Answer 4

writing code that can work with objects of multiple types and classes at once.

Question 5

a = Drawing.give_me_a_circle
puts a.what_am_i
a = Drawing::Circle.new
puts a.what_am_i
a = Circle.new
puts a.what_am_i

Answer 5

This is a circle
This is a circle
NameError: uninitialized constant Circle

Question 6

constants have scope within classes (t/f)

Answer 6

True Pi = 3.14 and Pi=3 in a class are different. class::Pi = 3
Pi = 3.14

Question 7

Modules

Answer 7

provide a structure to collect Ruby classes, methods, and constants into a single,
separately named and defined unit

Question 8

Namespaces

Answer 8

avoid name-related clashes.

Question 9

name conflict

Answer 9

As the last file loaded, it turns out to be the latter version of random, and a random letter
should appear onscreen. Unfortunately, however, it means your other randommethod has
been “lost.”
This situation is known as a name conflict,

Question 10

module NumberStuff
def NumberStuff.random
rand(1000000)
end
end
module LetterStuff
def LetterStuff.random
(rand(26) + 65).chr
end
end
puts NumberStuff.random
puts LetterStuff.random

Answer 10

value varies from 0 - 999999 and char from A-Z

Question 11

modules benefits

Answer 11

help solve conflicts providing namespaces that contain any number of classes, methods, and constants, and allow you to address them directly. Modules simply provide ways to organize methods, classes, and constants into separate namespaces.

Question 12

modules are classes (t/f)

Answer 12

False. you cannot define instances of a module, nor inherit from them.