Learn Ruby The Hard Way Exercise 41: Learning To Speak Object Oriented

Front 1

class

Back 1

Tell Ruby to make a new type of thing

Front 2

object

Back 2

Two meanings: the most basic yupe of thing, and any instance of some thing

Front 3

instance

Back 3

What you get when you tell Ruby to create a class

Front 4

def

Back 4

How you defin a function inside a class.

Front 5

@

Back 5

Inside the functions in a class, @ is a variable for the instance/object being accessed

Front 6

inheritance

Back 6

The concept that one class can inherit traits from another class, much like you and your parents

Front 7

composition

Back 7

The concept that a class can be composed of other classes as parts, much like how a car has wheels.

Front 8

attribute

Back 8

A property classes have that are from composition and are usually variables.

Front 9

is-a

Back 9

A phrase to say that something inherits from another, as in "salmon" is-a "fish"

Front 10

has-a

Back 10

A phrase to say that something is composed of other things or has a trait, as in "a salmon has-a mouth"

Front 11

class X < y

Back 11

"Make a class named X that is-a Y."

Front 12

class X: def initialize(J)

Back 12

"class X has-a initialize that takes a J parameter."

Front 13

class X: def M(J)

Back 13

"class X has-a function named M that takes a J parameter."

Front 14

foo = X()

Back 14

"Set foo to an instance of class X."

Front 15

foo.M(J)

Back 15

"From foo get the M function, and call it with parameter J."

Front 16

foo.k = Q

Back 16

"From foo get the K attribute and set it to Q."