OOP in Python

___________ are special methods that can be used to create and initialize an object

•  Constructors
• classes
• Interfaces
• Objects

Answer explanation

Constructors are special methods in object-oriented programming languages, including Python, that are automatically called when a new object of a class is created. In Python, the constructor method is defined as init(self, ...)

Fill in the blank to correctly define an initialization method for a class named Book that takes two parameters (besides self): title and author, and assigns them to instance variables.

(a)  

Answer explanation

The correct way to define the initialization method in Python involves specifying self as the first parameter in the method definition to refer to the instance of the class. The self parameter is also used to assign values to instance variables.

What does an object consist of?

• Methods

• Attributes

• Procedures

• Variables

Answer explanation

An object in Object-Oriented Programming consists of attributes and methods. Attributes hold the data (the state of the object), and methods define the behavior (what the object can do).

The ability of a programming language to process objects differently depending on their class is called ...

• Encapsulation

• Inheritance

• Polymorphism

• Instantiation

• Attributes

Answer explanation

Polymorphism allows objects of different classes to be treated through a common interface, enabling methods to use objects of any class that implements that interface.

You can instantiate an object more than once?

• True

• False

Answer explanation

Yes, you can instantiate an object more than once, creating multiple instances of a class, each with potentially unique attributes.

Which of the following statements correctly creates an instance of a class named Vehicle in Python?

• class Vehicle: new_vehicle = Vehicle()

• new_vehicle = Vehicle.class()

• new_vehicle = Vehicle()

• Vehicle new_vehicle = Vehicle()

Answer explanation

In Python, objects are instantiated from classes by calling the class as if it were a function, like Vehicle().

This creates a new instance of the class and assigns it to a variable (new_vehicle in this case).

Which of the following is true about inheritance in Python?

• Inheritance allows a class to inherit attributes and methods only from a single parent class.

• Inheritance allows a class to inherit attributes and methods from multiple parent classes, known as multiple inheritance.

• Inheritance is a mechanism where a class can copy methods from modules and packages.

• Inheritance is not supported in Python due to its dynamic nature.

Answer explanation

Python supports multiple inheritance, allowing a class to inherit from more than one base class. This feature enables the derived class to acquire attributes and methods from all the base classes it extends.

Fill in the blank to complete the definition related to the Open/Closed Principle of SOLID design principles:

"The Open/Closed Principle states that software entities (like classes, modules, functions, etc.) should be open for (a)   , but closed for modification."

Answer explanation

This principle encourages extending an entity's behavior without changing its source code, promoting reusability and flexibility in software design.

How is encapsulation typically achieved in Python?

• By declaring all variables within a class as private using the private keyword.

• By prefixing the name of a variable or method with a double underscore (__) to make it private.

• By using the @property decorator to strictly control access to class attributes.

• By making all methods static.

Answer explanation

Encapsulation in Python is typically achieved by making a variable or method private through the use of a double underscore prefix and/or using the @property decorator to control access to a class's attributes.

This allows for hiding and protecting member data from direct access and manipulation, adhering to the principles of encapsulation.

Which of the following statements accurately describe design patterns in Python?

• The Singleton pattern ensures a class has only one instance and provides a global point of access to that instance.

• The Builder pattern is used to separate the construction of a complex object from its representation, allowing the same construction process to create different representations.

• The Decorator pattern allows for the addition of new functionality to an existing object without modifying its structure.

• The Singleton pattern is primarily used to impose strict type-checking mechanisms in Python, similar to those found in statically typed languages.

Answer explanation

• The Singleton pattern restricts the instantiation of a class to one "single" instance. This is useful when exactly one object is needed to coordinate actions across the system.

• The Builder pattern provides a flexible solution to various object creation problems in object-oriented programming. It is especially useful when an object needs to be created with a large number of optional parameters.

• The Decorator pattern is a structural pattern used for dynamically adding behavior to an object at runtime. Decorators offer a flexible alternative to subclassing for extending functionality.