Deck 10: Astronomy: Creating Classes, Writing Constructors, Accessors, Mutators and Special Methods

Question 1

Every Python object is an instance of a(n):

A) data model.
B) class.
C) method.
D) algorithm.

Answer 1

B

Question 2

The details about what an object can do are called:

A) methods.
B) instance data.
C) models.
D) data types.

Answer 2

A

Question 3

Which of the following is one of Python's collection classes?

A) int
B) float
C) bool
D) str

Answer 3

D

Question 4

The ____ operator is used to invoke a method of an object.

A) dot
B) equals
C) dash
D) star

Question 5

Case Study 1:
>>> count = 1
>>> count = count + 1
>>> count
2
>>> count = count.__add__(1)
>>> count
3
>>>
>>> mylist.__getitem__(1)
66
-Refer to the session in the accompanying Case Study 1. What is the equivalent of the + operator?

A) __getItem__
B) __add__
C) ++
D) =

Question 6

Case Study 1:
>>> count = 1
>>> count = count + 1
>>> count
2
>>> count = count.__add__(1)
>>> count
3
>>>
>>> mylist.__getitem__(1)
66
-Refer to the session in the accompanying Case Study 1. What is the equivalent of the __getItem__ operator?

A) []
B) __add__
C) +
D) =

Question 7

What keyword defines a class in Python?

A) get
B) construct
C) def
D) class

Question 8

In Python, the constructor is always named:

A) __get__.
B) __init__.
C) constructor.
D) class.

Question 9

In a Python class, ____ refers to the object for which the method was called.

A) self
B) init
C) obj
D) class

Question 10

An accessor method is most likely to be used to implement:

A) mutator methods.
B) information hiding.
C) a constructor.
D) the dot operator.

Question 11

The print method invokes the ____ method of a class.

A) __print__
B) __str__
C) print
D) out

Question 12

____ objects store method names that refer to method definitions that are implemented by the class.

A) Mutator
B) Instance
C) Class definition
D) Self

Question 13

____ methods change an object in some way.

A) Accessor
B) Instance
C) Print
D) Mutator

Question 14

Preceding an instance variable name by two underscores____ the instance variable.

A) exposes
B) hides
C) mutates
D) accesses

Question 15

Case Study 2:
1. def createSSandAnimate():
2. ss = SolarSystem(2, 2)
3.
4. sun = Sun("SUN", 5000, 1000, 5800)
5. ss.addSun(sun)
6.
7. m = Planet("MERCURY", 19.5, 1000, .25, 0, 2, "blue")
8. ss.addPlanet(m)
9.
10. m = Planet("EARTH", 47.5, 5000, 0.3, 0, 2.0, "green")
11. ss.addPlanet(m)
12.
13. m = Planet("MARS", 50, 9000, 0.5, 0, 1.63, "red")
14. ss.addPlanet(m)
15.
16. m = Planet("JUPITER", 100, 49000, 0.7, 0, 1, "black")
17. ss.addPlanet(m)
18.
19. numTimePeriods = 2000
20. for aMove in range(numTimePeriods):
21. ss.movePlanets()
22.
23. ss.freeze()
24.
-Refer to the session in the accompanying Case Study 2. Which line(s) perform the actual work of the animation?

A) 4-5
B) 10-11
C) 16-17
D) 19-21

Question 16

Algorithms describe the solution to a problem in terms of the data needed to represent the problem instance and a set of steps necessary to produce the intended result.

Question 17

To create an instance of a class, call the __init__ method directly.

Question 18

Each object from a particular class has the same instance variables, but the values of those variables are different, therefore allowing the object to "behave" differently when asked to perform methods.

Question 19

The __class__ method is used to provide each object with a reference to the class definition object to which it belongs.

Question 20

The turtle module only allows one turtle to exist simultaneously in the same window.

Question 21

Match each definition with its term.
-Refers to the values of all instance variables for an object.

A) State
B) Class
C) Mutator method
D) Accessor method

Question 22

Match each definition with its term.
-Describes what an object will "look" like, what an object knows about itself, and what an object can do.

A) State
B) Class
C) Mutator method
D) Accessor method

Question 23

Match each definition with its term.
-Describes a procedure that changes an object in some way.

A) State
B) Class
C) Mutator method
D) Accessor method

Question 24

Match each definition with its term.
-Sometimes referred to as a "getter" method.

A) State
B) Class
C) Mutator method
D) Accessor method

Question 25

What does it mean to say that "Python supports the object-oriented programming paradigm?"

Question 26

What are some of the primitive and collection classes built into the Python language?

Question 27

What is a constructor method?

Question 28

What are accessor methods?

Question 29

What are mutator methods?

Question 30

Explain how method definitions are stored in Python.

Question 31

Explain the use of special class methods that Python provides.

Question 32

What is velocity? Provide an example to illustrate.

Question 33

Provide a high-level overview of the steps needed to create an animation of planets moving around the sun.