Deck 9: Design With Classes

Question 1

Python programmers typically capitalize their own class names to distinguish them from variable names.

Answer 1

True

Question 2

To overload an arithmetic operator, you just define a new method using the appropriate method name.

Answer 2

True

Question 3

Inheritance allows several different classes to use the same general method names.

Answer 3

False

Question 4

For data that are owned by individual objects, you must use class variables.

Question 5

The Python interpreter picks out equality from the other comparisons by looking for an __equals__ method when it encounters the == and != operators.

Question 6

Operator overloading is an example of an abstraction mechanism.

Question 7

Python has a built-in type for rational numbers called rational.

Question 8

A method automatically returns the value None when it includes no return statement.

Question 9

The scope of an instance variable is the entire module.

Question 10

If the parenthesized parent class name is omitted from the class definition, the new class is automatically made a subclass of self.

Question 11

Most object-oriented languages require the programmer to master the following techniques: data encapsulation, inheritance, and abstraction.

Question 12

The function call str(s) is equivalent to the method call s.__str__().

Question 13

In general, you should use class variables only for symbolic constants or to maintain data held in common by all objects of a class.

Question 14

Any object can be pickled before it is saved to a file, and then unpickled as it is loaded from a file into a program.

Question 15

Inheritance allows a class to automatically reuse and extend the code of similar but more general classes.

Question 16

The code x % y is actually shorthand for the code __mod__(x, y).

Question 17

The attributes of an object are represented as instance datum.

Question 18

To reduce a rational number to its lowest terms, you first compute the greatest common divisor (GCD) of the numerator and the denominator, using Euclid's algorithm.

Question 19

If the statements in the try clause raise no exceptions, the except clause is skipped and control proceeds to the end of the try-except statement.

Question 20

A class variable is visible to all instances of a class and does not vary from instance to instance.

Question 21

What statement is an accurate description of the concept of inheritance in object-oriented programming?

A) Inheritance is the restricting of the manipulation of an object's state by external users to a set of method calls.
B) Inheritance is allowing a class to automatically reuse and extend the code of a similar but more general class.
C) Inheritance is the use of code that is capable of making changes to itself during the execution process.
D) Inheritance is allowing the several different classes to use the same general method names.

Question 22

What statement is an accurate description of the concept of polymorphism in object-oriented programming?

A) Polymorphism is the restricting of the manipulation of an object's state by external users to a set of method calls.
B) Polymorphism is allowing a class to automatically reuse and extend the code of a similar but more general class.
C) Polymorphism is the use of code that is capable of making changes to itself during the execution process.
D) Polymorphism is allowing the several different classes to use the same general method names.

Question 23

At the top, or root of the class hierarchy is the most abstract class. What is the name of this class?

A) root
B) object
C) parentClass
D) Main

Question 24

Although Python is considered an object-oriented language, its syntax does not enforce data encapsulation.

Question 25

It is not usual to bother subclassing unless the two classes share a substantial amount of abstract behavior.

Question 26

You are utilizing the pickle.load function to load objects into a program from a file. However, your program raises an exception as soon as the end of the file is reached. What must you do?

A) Use an if-else statement to check if the load function is at the end of the file.
B) Use a nested loop to run the pickle.load function line by line.
C) Use a try-except statement to catch the exception and continue with the program.
D) Use the pickle.len() function to determine the size of the file, then pass the size to the pickle.load() function using the size key.

Question 27

The str method is a good example of a polymorphic method that appears throughout Python's system of classes.

Question 28

In the context of Python objects, what does the pickling process do?

A) It preserves objects by storing them in memory.
B) It preserves objects by storing them to a file.
C) It preserves objects by creating a sqlite database.
D) It preserves objects by adding them to the calling Python script file.

Question 29

What is the __str__ method used for?

A) It builds and returns a string representation of an object's state.
B) It is used to determine if a class attribute is a string.
C) It is used to initiate string values during instantiation.
D) It converts a string attribute within a class.

Question 30

Unlike other object-oriented languages, Python does not support polymorphic methods.

Question 31

If you wanted to overload the greater than or equal operator, what method name should you define?

A) __gte__
B) __gt__
C) __ge__
D) __geq__

Question 32

What function do you use to save an object utilizing the pickle module?

A) pickle.save
B) pickle.jar
C) pickle.dump
D) pickle.store

Question 33

What are the two parts of a rational number? (Choose two.)

A) dominator
B) denominator
C) numerator
D) terminator

Question 34

What is the process in which the Python virtual machine recycles its storage known as?

A) garbage collection
B) trash expunging
C) data dumping
D) tombstoning

Question 35

Objects in the natural world and objects in the world of artifacts can be classified using inheritance hierarchies.

Question 36

In Python, when does an object reach the end of its life?

A) When its timeout value has expired.
B) When it has been terminated by the destroy method.
C) When it has passed the last statement that uses it.
D) When it can no longer be referred to by the program that created it.

Question 37

What method is known as a class's constructor, because it is run automatically when a user instantiates the class?

A) __start__
B) __build__
C) __main__
D) __init__

Question 38

When the pickle.load function reaches the end of a file, what type of exception is raised?

A) IOError
B) EOFError
C) DataError
D) FileError

Question 39

What are the two access modes that are used when opening a file for input and output when pickling? (Choose two.)

A) r
B) rb
C) w
D) wb

Question 40

How could you overload the addition operator in the Python language?

A) You create a def statement with an asterisk, then specify math.__add__ as the method name.
B) You create a new class with the same name as the arithmetic class, and define the __add__ method.
C) You declare a new method with the same name, __add__, and define the method.
D) You create a Python script named __add__.py, and then define the new method in that script, then import it.

Question 41

What type of programming is defined by the term "imperative programming"?

A) Programming such that classes can be defined for objects and reused to define similar objects.
B) Programming that involves the use of input and output statements, assignment statements, and control statements for selection and iteration.
C) Programming that uses cooperating subprograms to solve problems.
D) Programming that views a program as a set of cooperating functions.

Question 42

The attributes of an object are represented as what type of variables?

A) state variables
B) substance variables
C) instance variables
D) self variables

Question 43

What can be used to describe and document the analysis and design of complex software systems?

A) Class Diagraming Language
B) Programming Structural Language
C) Direct Modeling Language
D) Unified Modeling Language

Question 44

What effect does using the model/view pattern of design have?

A) It divides the roles and responsibilities of the system between data management and user interface display.
B) It combines the roles and responsibilities of the system between data management and user interface display.
C) It involves the user in the defining of how data will be modeled by a program.
D) It involves the creation of a model GUI environment, and then involves the creation of views for the user to choose from.

Question 45

What concept within object-oriented programming involves the restriction of the manipulation of an object's state by external users to a set of method calls?

A) inheritance
B) polymorphism
C) data encapsulation
D) data modeling

Question 46

What two terms are used for the methods that are used to observe or modify the state of an object, respectively?

A) accessors
B) ingressors
C) modifiers
D) mutators

Question 47

As a rule of thumb, when should you include an __eq__ method in a class?

A) Always, because the comparison for equality is not compatible with classes.
B) Whenever a comparison for equality uses criterion other than object identity.
C) Only when you need to be able to make a comparison based on object identity.
D) Only if you plan to export the class as part of a module.

Question 48

What type of programming is defined by the term "functional programming"?

A) Programming utilizing cooperative subprograms to solve problems.
B) Programming using input and output statements, assignment statements, and control statements for selection and iteration.
C) Programming such that classes can be defined for objects and reused to define similar objects.
D) Programming using a set of cooperating functions rather than relying on assignment.

Question 49

What type of programming is defined by the term "procedural programming"?

A) Programming utilizing cooperative subprograms to solve problems.
B) Programming using input and output statements, assignment statements, and control statements for selection and iteration.
C) Programming such that classes can be defined for objects and reused to define similar objects.
D) Programming using a set of cooperating functions rather than relying on assignment.

Question 50

Regarding class variables, what statement is accurate?

A) A class variable is only visible to a single instance of a class.
B) A class variable is visible only to methods inside a class.
C) A class variable is visible to all instances of a class, but can vary from instance to instance.
D) A class variable is visible to all instances of a class, and does not vary from instance to instance.