Basics

Question 1

Ruby’s class for initializing I/O streams.

Answer 1

IO

Question 2

Method for iterating through an array and storing the results in a new array

Answer 2

Array#collect

ie: array.collect { |elem| elem * 2 }

Question 3

Method for iterating through an array and not storing the results in a new array

Answer 3

Array#each

ie: array.each { |item| puts item }

Question 4

String method for breaking up the string into an array at certain points

Answer 4

String#split

Question 5

||

this operator means…

Answer 5

or

Question 6

&&

this operator means…

Answer 6

and

Question 7

number > 0 ? “#{number} is positive” : “#{number} is negative”
this is an example of a ________ expression

Answer 7

ternary expression

Question 8

[1, 2, 3][2]

this method will return:

Answer 8

3

the 2th index

Question 9

[1, 2, 3].

this method will return:

Answer 9

3

the last index

Question 10

Hash method which returns an array of all the hash’s keys

Answer 10

Hash#keys

Question 11

method which returns an object’s class

Answer 11

Object#class

Question 12

“hello”.is_a? String

what will this return and what is the method doing?

Answer 12

true

the method returns a boolean on whether the object is of the argument class

Question 13

For a class to justify its existence, it needs to have two distinct features:

Answer 13

1. State

2. Behavior

Question 14

A ______ is a piece of code that you can store in a variable, and is an object.

Answer 14

lambda

Question 15

a piece of code that can’t be stored in a variable and isn’t an object.

Answer 15

block

Question 16

_______ only hold behaviour, unlike classes, which hold both behaviour and state.

Answer 16

Modules

Question 17

Symbol for the constant lookup operator

Answer 17

::

Question 18

What is the scope of a local variable?

Answer 18

A local variable is accessible only in the method that it is defined.

Question 19

What is a getter method?

Answer 19

A getter method is used within an object. It returns the value of a(n) instance variable(s)

Question 20

What is a setter method?

Answer 20

A setter method is used within an object. It can alter the value of a(n) instance variable(s)

Question 21

What is attr_writer?

Answer 21

attr_writer is a shortcut for a setter method. It allows the passed instance variable to be changed.

Question 22

What is attr_reader?

Answer 22

attr_reader is a shortcut for a getter method/ It allows an instance variable to have its value returned.

Question 23

What is a class variable and what is its notation? And how do changes to a class variable work?

Answer 23

Notation: @@ ie: -|@@class_variable|-
It is a variable that is the same for all instances and children of the class in which the class variable is defined. A change to the class variable will be reflected in all instances/children of that class.

Question 24

How accessible are class instance variables?

Answer 24

Class instance variables are available only in class methods

Question 25

List the quick summary of RubyMonks review of class variables.

Answer 25

Instance variables are available only for instances of a class. They look like @name. Class variables are available to both class methods and instance methods. They look like @@name

It is almost always a bad idea to use a class variable to store state. There are only a very few valid use cases where class variables are the right choice.

Prefer class instance variables over class variables when you do really need store data at a class level. Class instance variables use the same notation as that of an instance variable. But unlike instance variables, you declare them inside the class definition directly.