Object-Oriented Programming Concepts

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Questions and Answers

What is the primary purpose of a constructor in Python?

To define a class method

To declare and initialize instance variables of a class (correct)

To access class variables

To create multiple instances of a class

What happens if a constructor is not defined in a Python class?

A default constructor is provided by Python (correct)

The class variables are not initialized

An error is raised

The class cannot be instantiated

How are class variables accessed in Python?

Using the constructor

Using the dot notation with the instance name

Using the dot notation with the class name (correct)

Using the class method

What is the purpose of a non-parameterized constructor?

To initialize objects with default values Signup and view all the answers

How many copies of a static variable are created in a Python class?

One copy per class Signup and view all the answers

What is the purpose of object initialization in Python?

To initialize the attributes of an object Signup and view all the answers

What is the difference between object creation and object initialization in Python?

Object creation is the process of creating an instance, while object initialization is the process of initializing the attributes Signup and view all the answers

How are instance attributes accessed or modified in Python?

Using the dot notation with the instance name Signup and view all the answers

What is the purpose of a parameterized constructor in Python?

To pass different values to each object at the time of creation Signup and view all the answers

What is the first parameter to a constructor in Python?

Self keyword Signup and view all the answers

What is the purpose of the self keyword in a constructor?

To reference the object being constructed Signup and view all the answers

How do you define a constructor with default values in Python?

By assigning default values to the parameters in the constructor Signup and view all the answers

What is the purpose of the setRadius method in the Circle class?

To modify the radius of an existing circle object Signup and view all the answers

How do you access the properties of an object in Python?

Using the dot notation (e.g. object.property) Signup and view all the answers

What is the purpose of the getPerimeter method in the Circle class?

To calculate the perimeter of the circle Signup and view all the answers

What is the default value of the radius in the Circle class?

1 Signup and view all the answers

What is the purpose of a class in Python?

To define a blueprint for creating multiple objects Signup and view all the answers

What is the difference between a class and an object in Python?

A class is a blueprint for creating multiple objects, and an object is an instance of a class Signup and view all the answers

What is the purpose of the `init` method in a class?

To initialize the attributes of an object Signup and view all the answers

How do objects access their attributes in Python?

Using the <code>self</code> keyword, followed by the attribute name Signup and view all the answers

What is the difference between instance variables and class variables?

Instance variables are unique to each object, while class variables are shared across multiple objects Signup and view all the answers

What happens when you create multiple objects from a class?

Each object has its own copy of the instance variables Signup and view all the answers

How do you create an object from a class in Python?

Using the class name, followed by the attribute values in parentheses Signup and view all the answers

What is the purpose of the `self` parameter in an instance method?

To refer to the object that the method is being called on Signup and view all the answers

Study Notes

Classes and Objects

A class is a user-defined data structure that binds data members and methods into a single unit.
A class is a blueprint or code template for object creation.
An object is an instance of a class, a collection of attributes (variables) and methods.
Every object has the following properties: identity, state, and behavior.

Constructors

A constructor is a special method used to create and initialize an object of a class.
The constructor is executed automatically at the time of object creation.
The primary use of a constructor is to declare and initialize data members/instance variables of a class.
A default constructor is provided by Python if no constructor is defined.
A default constructor is an empty constructor without a body that initializes objects.

Types of Constructors

Non-Parametrized Constructor: a constructor without any arguments, used to initialize each object with default values.
Parameterized Constructor: a constructor with defined parameters or arguments, used to pass different values to each object at the time of creation.
Constructor With Default Values: allows defining a constructor with default values, which are used if no arguments are passed to the constructor at the time of object creation.

Accessing Properties and Assigning Values

Instance attributes can be accessed or modified using the dot notation: instance_name.attribute_name.
Class variables can be accessed or modified using the class name.
Objects do not share instance attributes, but every object has its own copy of the instance attribute.
All instances of a class share the class variables.

Class Methods

There are three types of methods that can be defined inside a class.

Example of Class Definition

A class is defined using the class keyword.
The syntax to create a class is class Person: ....
The __init__ method is a special method used to create and initialize an object of a class.
The self keyword is a reference to the object being constructed.

Example of Object Creation

An object is created using the class name, e.g., jessa = Person('Jessa', 'Female', 'Software Engineer').
Methods can be called on an object using the dot notation, e.g., jessa.show() and jessa.work().

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Description

This quiz covers the basics of object-oriented programming, including static variables, instance attributes, class methods, and constructors in Python.