Advanced Python SEM 2 Uint-3 Question Bank Answer

 FY.Bsc.Cs Sem-2 Based on Mumbai Unversity 

 Advanced Python SEM 2 Uint-3 Question Bank Answer:-

1) Describe various OOP features in Python.

In Python, Object-Oriented Programming (OOP) features play a crucial role in structuring code and promoting reusability. Here are some key OOP features in Python:

  1. Classes and Objects:

    • A class is a blueprint for creating objects. It defines attributes (variables) and methods (functions) that the objects will have.
    • An object is an instance of a class. It represents a real-world entity and can store data and perform actions.

  2. Encapsulation:

    • Encapsulation is the bundling of data (attributes) and methods that operate on the data within a class.
    • It helps in hiding the internal state of an object and restricting direct access to certain components, promoting data security and integrity.

  3. Inheritance:

    • Inheritance allows a new class (derived class) to inherit attributes and methods from an existing class (base class or parent class).
    • It promotes code reusability and the creation of a hierarchy of classes with shared characteristics.

  4. Polymorphism:

    • Polymorphism allows objects of different classes to be treated as objects of a common superclass.
    • It enables methods to be written to handle objects of multiple types, promoting flexibility and extensibility in code.

  5. Abstraction:

    • Abstraction involves hiding complex implementation details and showing only the essential features of an object.
    • It allows programmers to focus on what an object does rather than how it does it, enhancing code readability and maintainability.

  6. Method Overriding:

    • Method overriding occurs when a subclass provides a specific implementation of a method that is already provided by its superclass.
    • It allows a subclass to customize or extend the behavior of inherited methods.

  7. Destructor:

    • A destructor is a special method (del) that is automatically called when an object is destroyed or goes out of scope.
    • It is used for performing cleanup activities such as closing file handles or releasing resources.

 2) Write a note on classes and objects in Python. 

Classes:

  • A class in Python is a blueprint or template for creating objects. It defines the attributes (data) and methods (functions) that the objects of the class will have.
  • Classes are defined using the class keyword followed by the class name. For example:
    class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
  • The __init__ method is a special method called the constructor, used to initialize the object's attributes when an object is created.
  • Attributes are accessed using dot notation (object.attribute_name) within the class or its methods.

Objects:

  • An object is an instance of a class. It represents a specific entity based on the class blueprint.
  • Objects have attributes (variables) and methods (functions) associated with them, inherited from the class.
  • Objects are created by calling the class as if it were a function, which invokes the constructor to initialize the object. For example:
    person1 = Person("Alice", 30)
  • Multiple objects can be created from the same class, each maintaining its own set of attributes and methods.

Key Points:

  • Classes provide a way to bundle data and functionality together, promoting code organization and reusability.
  • Objects are instances of classes and represent specific entities with their own state and behavior.
  • Classes can be used to create custom data types and define complex behaviors for objects.
  • Inheritance allows classes to inherit attributes and methods from other classes, promoting code reuse and hierarchy.
  • Encapsulation ensures that the internal state of an object is protected and accessed only through defined methods.

3) What is inheritance in Python? Give its syntax along with an example.

Inheritance in Python:

Inheritance is a key feature of Object-Oriented Programming (OOP) that allows a new class (derived class) to inherit attributes and methods from an existing class (base class or parent class). This promotes code reusability and the creation of a hierarchy of classes with shared characteristics.

Syntax of Inheritance in Python:

class BaseClass:
    # Base class attributes and methods

class DerivedClass(BaseClass):
    # Derived class attributes and methods

Example of Inheritance in Python:

# Base class
class Animal:
    def __init__(self, name):
        self.name = name

    def speak(self):
        print(f"{self.name} makes a sound")

# Derived class inheriting from Animal
class Dog(Animal):
    def __init__(self, name, breed):
        super().__init__(name)
        self.breed = breed

    def speak(self):
        print(f"{self.name} barks")

# Creating objects and invoking methods
animal = Animal("Generic Animal")
animal.speak()

dog = Dog("Buddy", "Labrador")
dog.speak()

In this example:

  • The Animal class is the base class with an __init__ method to initialize the name attribute and a speak method.
  • The Dog class is the derived class that inherits from Animal and adds a breed attribute. It overrides the speak method to provide a specific behavior for dogs.
  • The super() function is used to call the base class constructor in the derived class constructor to initialize the name attribute.
  • Objects of both classes are created, and their speak methods are invoked, demonstrating method overriding in inheritance.

Inheritance in Python allows for the creation of a hierarchy of classes, where derived classes can reuse and extend the functionality of base classes, leading to more organized and efficient code structures.


 4) Describe constructors in Python.

Constructors in Python:

In Python, a constructor is a special method that is automatically called when an object is created. It is used to initialize the object's attributes or perform any setup required for the object. The constructor method in Python is denoted by __init__.

Key Points about Constructors:

  1. Initialization: Constructors are used to initialize the attributes of an object when it is created. This helps in setting up the initial state of the object.

  2. Automatic Invocation: The constructor is automatically called when an object is created from a class. It is not required to explicitly call the constructor method.

  3. Syntax: The constructor method in Python is defined within a class using the __init__ method. It takes self as the first parameter, followed by any other parameters required for initialization.

  4. Multiple Constructors: A class can have only one constructor, which is the __init__ method. However, you can define multiple constructors using different parameter lists by utilizing default parameter values or using optional arguments.

Example of Constructors in Python:

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def display(self):
        print(f"Name: {self.name}, Age: {self.age}")

# Creating objects and invoking methods
person1 = Person("Alice", 30)
person1.display()

person2 = Person("Bob", 25)
person2.display()

In this example:

  • The Person class has a constructor __init__ that initializes the name and age attributes of the object.
  • When objects person1 and person2 are created from the Person class, the constructor is automatically called to set the initial values for name and age.
  • The display method is used to print the details of the person object.

 5) Explain polymorphism in python.

Polymorphism in Python:

Polymorphism is a fundamental concept in Object-Oriented Programming (OOP) that allows objects to be treated as instances of their parent class or as instances of their own class. It enables objects to exhibit different behaviors based on their data types or class hierarchy. In Python, polymorphism is achieved through method overriding and operator overloading.

Key Points about Polymorphism:

  1. Method Overriding: Polymorphism in Python is often implemented through method overriding, where a method in a subclass has the same name as a method in its superclass. The subclass method overrides the behavior of the superclass method.

  2. Operator Overloading: Python supports operator overloading, allowing operators like +, -, *, etc., to be used with different data types or classes. The behavior of these operators can be defined differently for different classes.

  3. Dynamic Typing: Python is a dynamically typed language, meaning that the type of an object is determined at runtime. This dynamic typing contributes to the flexibility and ease of implementing polymorphism in Python.

Example of Polymorphism in Python:

class Animal:
    def speak(self):
        print("Animal makes a sound")

class Dog(Animal):
    def speak(self):
        print("Dog barks")

class Cat(Animal):
    def speak(self):
        print("Cat meows")

# Polymorphic behavior
def make_sound(animal):
    animal.speak()

# Creating objects and invoking methods
animal = Animal()
dog = Dog()
cat = Cat()

make_sound(animal)  # Output: Animal makes a sound
make_sound(dog)     # Output: Dog barks
make_sound(cat)     # Output: Cat meows

In this example:

  • The Animal class has a speak method that prints a generic sound.
  • The Dog and Cat classes inherit from the Animal class and override the speak method with specific sounds for dogs and cats.
  • The make_sound function demonstrates polymorphism by accepting any object that has a speak method and calling that method, resulting in different behaviors based on the object type.

 6) Explain various types of methods available in OOP behavior of Python. 

Types of Methods in Object-Oriented Programming (OOP) in Python:

In Python, methods are functions defined within a class that operate on objects created from that class. Different types of methods in OOP behavior in Python include instance methods, class methods, and static methods. Each type of method serves a specific purpose and has its own characteristics.

1. Instance Methods:

  • Definition: Instance methods are the most common type of methods in Python classes. They operate on an instance of a class and have access to the instance attributes.
  • Syntax: Instance methods take self as the first parameter, which refers to the instance of the class.
  • Usage: Instance methods can modify object state, access instance attributes, and interact with other instance methods.
  • Example:
class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def display_info(self):
        print(f"Name: {self.name}, Age: {self.age}")

person = Person("Alice", 30)
person.display_info()

2. Class Methods:

  • Definition: Class methods are methods that are bound to the class itself rather than an instance of the class. They can access and modify class-level attributes.
  • Syntax: Class methods are defined using the @classmethod decorator and take cls as the first parameter, referring to the class itself.
  • Usage: Class methods are often used for creating factory methods or performing operations that involve the class itself.
  • Example:
class Circle:
    pi = 3.14

    @classmethod
    def get_pi(cls):
        return cls.pi

print(Circle.get_pi())  # Output: 3.14

3. Static Methods:

  • Definition: Static methods are independent of the class and do not have access to instance or class attributes. They are defined using the @staticmethod decorator.
  • Syntax: Static methods do not take self or cls as parameters and are used when a method does not require access to instance or class data.
  • Usage: Static methods are useful for utility functions that are related to the class but do not depend on instance or class state.
  • Example:
class MathOperations:
    @staticmethod
    def add(x, y):
        return x + y

print(MathOperations.add(5, 3))  # Output: 8


7) What type of variables are available in Python class. Explain them. 

Types of Variables in Python Class:

In Python classes, there are mainly two types of variables: instance variables and class variables. These variables play a crucial role in defining the attributes and properties of objects created from a class.

1. Instance Variables:

  • Definition: Instance variables are unique to each instance of a class. They are defined within methods of a class and are specific to that instance.
  • Scope: Instance variables are accessible only within the scope of the instance (object) they belong to.
  • Usage: Instance variables store data that is unique to each object and can vary from one object to another.
  • Example:
class Person:
    def __init__(self, name, age):
        self.name = name  # Instance variable
        self.age = age    # Instance variable

person1 = Person("Alice", 30)
person2 = Person("Bob", 25)
print(person1.name)  # Output: Alice
print(person2.name)  # Output: Bob

2. Class Variables:

  • Definition: Class variables are shared among all instances of a class. They are defined within the class but outside any method.
  • Scope: Class variables are accessible by all instances of the class as well as the class itself.
  • Usage: Class variables store data that is common to all instances of the class and can be used to define attributes that are shared across all objects.
  • Example:
class Circle:
    pi = 3.14  # Class variable

    def __init__(self, radius):
        self.radius = radius  # Instance variable

    def calculate_area(self):
        return Circle.pi * self.radius**2

circle1 = Circle(5)
circle2 = Circle(7)
print(circle1.calculate_area())  # Output: 78.5
print(circle2.calculate_area())  # Output: 153.86

Key Differences:

  • Instance variables are unique to each object and are used to store object-specific data, while class variables are shared among all objects of the class.
  • Instance variables are defined within methods using self, whereas class variables are defined directly within the class.
  • Changes to class variables affect all instances, while changes to instance variables are specific to each instance.

8) Write a note on inner classes.

Inner Classes in Python:

In Python, inner classes, also known as nested classes, are classes defined within another class. These inner classes have access to the outer class's attributes and methods, and they can be used to logically group related classes together. Inner classes provide a way to organize and encapsulate code within a class hierarchy.

Key Points about Inner Classes:

  1. Definition: An inner class is a class defined inside another class, allowing for a hierarchical structure of classes within a single class definition.

  2. Access to Outer Class Members: Inner classes have access to the attributes and methods of the outer class. This allows for better encapsulation and organization of related classes.

  3. Scope: Inner classes are scoped within the outer class, meaning they are only accessible within the context of the outer class.

  4. Encapsulation: Inner classes can be used to encapsulate functionality that is closely related to the outer class, keeping the code modular and organized.

  5. Example:

class OuterClass:
    def __init__(self):
        self.outer_attr = "Outer Attribute"

    class InnerClass:
        def __init__(self):
            self.inner_attr = "Inner Attribute"

        def display(self):
            print("Inner Attribute:", self.inner_attr)

# Creating an instance of the outer class
outer_obj = OuterClass()

# Creating an instance of the inner class
inner_obj = outer_obj.InnerClass()
inner_obj.display()

  1. Use Cases: Inner classes are useful when:

    • There is a need to logically group classes together.
    • The inner class is closely related to the outer class and its functionality.
    • Encapsulation of related classes is desired within a single class definition.

  2. Code Organization: By using inner classes, developers can improve code organization, maintainability, and readability by grouping related classes together and keeping the code modular.

  3. Limitations: While inner classes offer benefits in terms of code organization, they should be used judiciously to avoid overly complex class hierarchies and maintain clarity in the code structure.


 9) Explain various types of inheritance in Python. 

Types of Inheritance in Python:

Inheritance is a fundamental concept in object-oriented programming that allows a new class (derived class) to inherit attributes and methods from an existing class (base class). In Python, there are several types of inheritance that can be used to create class hierarchies and reuse code efficiently.

1. Single Inheritance:

  • Definition: Single inheritance involves one base class and one derived class. The derived class inherits attributes and methods from the base class.
  • Syntax:
class BaseClass:
    # Base class attributes and methods

class DerivedClass(BaseClass):
    # Derived class attributes and methods
  • Example: A Car class inheriting from a Vehicle class.

2. Multiple Inheritance:

  • Definition: Multiple inheritance involves a derived class inheriting from multiple base classes. The derived class can access attributes and methods from all the base classes.
  • Syntax:
class BaseClass1:
    # Base class 1 attributes and methods

class BaseClass2:
    # Base class 2 attributes and methods

class DerivedClass(BaseClass1, BaseClass2):
    # Derived class attributes and methods
  • Example: A HybridCar class inheriting from both ElectricCar and GasolineCar classes.

3. Multilevel Inheritance:

  • Definition: Multilevel inheritance involves a chain of inheritance where a class is derived from a derived class. This creates a hierarchy of classes.
  • Syntax:
class BaseClass:
    # Base class attributes and methods

class IntermediateClass(BaseClass):
    # Intermediate class attributes and methods

class DerivedClass(IntermediateClass):
    # Derived class attributes and methods
  • Example: A Animal class inherited by Mammal class, which is further inherited by Dog class.

4. Hierarchical Inheritance:

  • Definition: Hierarchical inheritance involves multiple derived classes inheriting from a single base class. This creates a hierarchy where different classes share common attributes and methods from the base class.
  • Syntax:
class BaseClass:
    # Base class attributes and methods

class DerivedClass1(BaseClass):
    # Derived class 1 attributes and methods

class DerivedClass2(BaseClass):
    # Derived class 2 attributes and methods
  • Example: A Shape class inherited by Rectangle and Circle classes.

5. Hybrid Inheritance:

  • Definition: Hybrid inheritance is a combination of multiple types of inheritance. It involves a mix of single, multiple, multilevel, and hierarchical inheritance.
  • Syntax: Combination of inheritance types as needed.
  • Example: A complex class hierarchy involving multiple base and derived classes with different inheritance relationships.

10) What Is Duck Typing? How is it implemented in Python? 

Duck Typing in Python:

Duck typing is a concept in programming that focuses on an object's behavior rather than its type. The term "duck typing" comes from the saying, "If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck." In Python, duck typing allows objects to be used based on their behavior and capabilities rather than their explicit type.

Key Points about Duck Typing:

  1. Behavior-Based: Duck typing emphasizes the presence of certain methods or behaviors in an object rather than its specific type or class.

  2. Dynamic Typing: Python is a dynamically typed language, meaning that the type of an object is determined at runtime. Duck typing leverages this dynamic typing feature.

  3. Example: If an object has a quack() method and a swim() method, it can be considered a duck-like object, regardless of whether it is explicitly of a Duck class.

  4. Implementation in Python:

    • In Python, duck typing is implemented through the principle of "Easier to ask for forgiveness than permission" (EAFP).
    • Instead of checking the type of an object before performing an operation, Python code typically tries to perform the operation and handles any exceptions that may arise if the object does not support it.
    • This approach allows Python to focus on the object's behavior rather than its type, promoting flexibility and code reusability.

Example of Duck Typing in Python:

class Duck:
    def quack(self):
        print("Quack!")

class Person:
    def quack(self):
        print("I can quack like a duck!")

def make_quack(obj):
    obj.quack()

# Objects with a 'quack' method can be passed to make_quack
duck = Duck()
person = Person()

make_quack(duck)    # Output: Quack!
make_quack(person)  # Output: I can quack like a duck!

In the example above, both the Duck class and the Person class have a quack() method. The make_quack() function accepts any object that has a quack() method, demonstrating duck typing in action. As long as an object behaves like a duck (i.e., has a quack() method), it can be treated as a duck-like object.


11) Write a note on method overriding in Python.

Method Overriding in Python:

Method overriding is a powerful object-oriented programming concept in Python that allows a subclass to provide a specific implementation of a method that is already defined in its superclass. When a method in a subclass has the same name, parameters, and return type as a method in its superclass, the subclass method overrides the superclass method.

Key Points about Method Overriding:

  1. Inheritance Requirement: Method overriding is closely related to inheritance, where a subclass inherits methods and attributes from its superclass.

  2. Polymorphism: Method overriding is a form of polymorphism in Python, where objects can exhibit different behaviors based on their context.

  3. Flexibility: Method overriding provides flexibility in object-oriented design by allowing subclasses to customize or extend the behavior of inherited methods.

  4. Syntax: To override a method in Python, the subclass defines a method with the same name as the superclass method. This process is also known as redefining a method.

  5. Invocation: When an overridden method is called on an object of the subclass, the subclass method is executed instead of the superclass method.

Example of Method Overriding in Python:

class Animal:
    def speak(self):
        print("Animal speaks")

class Dog(Animal):
    def speak(self):
        print("Dog barks")

# Creating objects
animal = Animal()
dog = Dog()

# Calling the speak method
animal.speak()  # Output: Animal speaks
dog.speak()     # Output: Dog barks

In the example above, the Dog class inherits the speak() method from the Animal class. However, the Dog class overrides the speak() method with its own implementation. When the speak() method is called on a Dog object, the overridden method in the Dog class is executed, demonstrating method overriding.



 12) How is operator overloading achieved in Python? Give its example. 

Operator Overloading in Python:

Operator overloading in Python allows developers to define custom behavior for operators such as +, -, *, /, ==, !=, etc., when applied to objects of user-defined classes. By overloading operators, Python classes can define how operators should work with instances of the class, providing flexibility and customization in object-oriented programming.

Key Points about Operator Overloading:

  1. Magic Methods: Operator overloading is achieved in Python by implementing special methods known as magic methods or dunder methods (methods with double underscores __). These methods define the behavior of operators when applied to objects of a class.

  2. Customized Behavior: By overloading operators, developers can define custom behavior for operators based on the specific requirements of their classes. This allows for more intuitive and expressive code.

  3. Enhanced Flexibility: Operator overloading enhances the flexibility of Python classes by enabling them to support standard operators in a way that makes sense for the class's objects.

  4. Example Operators: Common operators that can be overloaded include arithmetic operators (+, -, *, /), comparison operators (==, !=, <, >, <=, >=), and more.

Example of Operator Overloading in Python:

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __add__(self, other):
        return Point(self.x + other.x, self.y + other.y)

    def __eq__(self, other):
        return self.x == other.x and self.y == other.y

    def __str__(self):
        return f"({self.x}, {self.y})"

# Creating Point objects
p1 = Point(2, 3)
p2 = Point(4, 5)

# Overloading the addition operator (+)
p3 = p1 + p2
print(p3)  # Output: (6, 8)

# Overloading the equality operator (==)
print(p1 == p2)  # Output: False

In the example above, the Point class overloads the addition operator + and the equality operator == by implementing the __add__() and __eq__() magic methods, respectively. When the + operator is used with Point objects, the __add__() method is called to perform the addition of coordinates. Similarly, the __eq__() method defines how equality is determined between two Point objects.



13) Explain multilevel inheritance with an example. 

Multilevel Inheritance in Python:

Multilevel inheritance is a type of inheritance in object-oriented programming where a class inherits from another class, and then another class inherits from the derived class. This creates a hierarchical relationship between classes, with each subclass inheriting attributes and methods from its immediate superclass as well as from all the superclasses above it in the hierarchy.

Key Points about Multilevel Inheritance:

  1. Hierarchical Structure: In multilevel inheritance, classes are organized in a hierarchical structure, with each subclass inheriting properties from its immediate parent class and all the ancestor classes above it.

  2. Code Reusability: Multilevel inheritance promotes code reusability by allowing subclasses to inherit attributes and methods from multiple levels of the class hierarchy.

  3. Flexibility: This type of inheritance provides flexibility in designing class relationships and allows for the creation of specialized subclasses that build upon the functionality of their parent classes.

  4. Example Scenario: A common scenario for multilevel inheritance is when there are multiple levels of specialization in a system, where each subclass adds more specific features to the classes above it in the hierarchy.

Example of Multilevel Inheritance in Python:

# Parent class
class Animal:
    def speak(self):
        print("Animal speaks")

# Child class inheriting from Animal
class Dog(Animal):
    def bark(self):
        print("Dog barks")

# Grandchild class inheriting from Dog
class Labrador(Dog):
    def color(self):
        print("Labrador is golden in color")

# Creating objects
labrador = Labrador()

# Calling methods from different levels of the hierarchy
labrador.speak()  # Output: Animal speaks
labrador.bark()   # Output: Dog barks
labrador.color()  # Output: Labrador is golden in color

In the example above, we have a hierarchy of classes where Labrador is a subclass of Dog, which in turn is a subclass of Animal. The Labrador class inherits the speak() method from Animal, the bark() method from Dog, and defines its own color() method.



14) Write a note on constructor in inheritance. 

Constructor in Inheritance in Python:

Inheritance in object-oriented programming allows a subclass to inherit attributes and methods from its superclass. When dealing with constructors in inheritance, it is essential to understand how constructors are handled in the context of inheritance in Python.

Key Points about Constructors in Inheritance:

  1. Constructor Inheritance: In Python, when a subclass is created, it can inherit the constructor of its superclass. This means that if the subclass does not have its own constructor, it will automatically inherit the constructor of the superclass.

  2. super() Function: The super() function is commonly used in Python to call the constructor of the superclass from the subclass. This allows the subclass to initialize the attributes inherited from the superclass before adding its own attributes.

  3. Constructor Overriding: If a subclass defines its own constructor, it can override the constructor of the superclass. In this case, the subclass constructor can perform additional initialization specific to the subclass while still utilizing the superclass constructor using super().

  4. Initialization Order: When dealing with multiple levels of inheritance, constructors are called in a specific order known as the Method Resolution Order (MRO). The MRO ensures that constructors are called from the most specific class to the least specific class in the inheritance hierarchy.

Example of Constructor in Inheritance:

# Parent class with a constructor
class Parent:
    def __init__(self, name):
        self.name = name
        print("Parent constructor called")

# Child class inheriting from Parent
class Child(Parent):
    def __init__(self, name, age):
        super().__init__(name)  # Calling parent class constructor
        self.age = age
        print("Child constructor called")

# Creating object of Child class
child_obj = Child("Alice", 10)

In the example above, the Child class inherits from the Parent class. The Child class defines its own constructor that takes name and age as parameters. Inside the Child class constructor, super().__init__(name) is used to call the constructor of the Parent class before initializing the age attribute specific to the Child class.


15) Write a note on a destructor in Python class. 

Destructor in Python Classes:

In Python, a destructor is a special method that is automatically called when an object is no longer needed or is about to be destroyed. The destructor method is used to perform cleanup activities before the object is removed from memory. In object-oriented programming, a destructor is the opposite of a constructor, which is used to initialize an object.

Key Points about Destructors in Python Classes:

  1. Purpose of Destructors: Destructors are used to release resources, close connections, or perform any cleanup tasks before an object is destroyed. Common use cases for destructors include closing files, releasing memory, or closing database connections.

  2. __del__ Method: In Python, the destructor method is defined using the special method __del__(). When an object is deleted or garbage collected, the __del__() method is automatically called to clean up resources associated with the object.

  3. Automatic Invocation: Destructors are automatically invoked by the Python interpreter when an object is no longer referenced or when the program exits. Developers do not need to explicitly call the destructor method; it is handled by the Python runtime.

  4. Cleanup Activities: Inside the destructor method, developers can include code to release resources, close connections, or perform any necessary cleanup operations. This ensures that resources are properly managed and released when an object is no longer in use.

Example of Destructor in Python Class:

class FileHandler:
    def __init__(self, filename):
        self.filename = filename
        print(f"File {self.filename} opened")

    def read_file(self):
        print(f"Reading from file {self.filename}")

    def __del__(self):
        print(f"Closing file {self.filename}")
        # Code to close the file or release resources

# Creating object of FileHandler class
file_obj = FileHandler("example.txt")
file_obj.read_file()

# Object is deleted or goes out of scope
# Destructor will be automatically called

In the example above, the FileHandler class has a constructor __init__() that opens a file when an object is created. The class also defines a destructor __del__() that closes the file when the object is deleted or goes out of scope. The destructor ensures that the file is properly closed and resources are released when the object is no longer needed.



16) Differentiate between abstract class and interface of Python. 

Abstract Class vs. Interface in Python:

In Python, both abstract classes and interfaces are used to define blueprints for classes and enforce certain rules or structures. While they serve similar purposes, there are key differences between abstract classes and interfaces in Python.

Abstract Class:

  1. Definition: An abstract class is a class that cannot be instantiated on its own and is designed to be subclassed. It may contain abstract methods (methods without implementation) that must be implemented by its subclasses.

  2. Creation: Abstract classes are created using the abc (Abstract Base Classes) module in Python.

  3. Usage: Abstract classes can contain both abstract methods (methods without implementation) and concrete methods (methods with implementation).

  4. Inheritance: Subclasses of an abstract class must implement all the abstract methods defined in the abstract class.

  5. Object Creation: Objects cannot be created from an abstract class directly; they can only be created from its concrete subclasses.

  6. Example:

from abc import ABC, abstractmethod

class Shape(ABC):
    @abstractmethod
    def area(self):
        pass

class Circle(Shape):
    def area(self):
        return 3.14 * self.radius * self.radius

Interface:

  1. Definition: An interface in Python is a class that contains only abstract methods. It defines a contract for classes that implement it, specifying the methods that must be implemented.

  2. Creation: Interfaces are not natively supported in Python, as the language does not have a specific interface keyword. However, interfaces can be emulated using abstract classes with all methods being abstract.

  3. Usage: Interfaces contain only method signatures without any implementation details. Classes that implement an interface must provide concrete implementations for all the methods defined in the interface.

  4. Inheritance: Classes can implement multiple interfaces, allowing them to define behavior specified by multiple interfaces.

  5. Object Creation: Objects cannot be created from an interface directly; they can only be created from classes that implement the interface.

  6. Example:

from abc import ABC, abstractmethod

class Printable(ABC):
    @abstractmethod
    def print(self):
        pass

class Document(Printable):
    def print(self):
        print("Printing document...")

Key Differences:

  1. Object Creation: Objects cannot be created from either abstract classes or interfaces directly. They can only be created from concrete subclasses that implement the abstract methods.

  2. Method Implementation: Abstract classes can have both abstract and concrete methods, while interfaces contain only abstract method signatures.

  3. Inheritance: Abstract classes support single inheritance, while interfaces allow classes to implement multiple interfaces.

  4. Purpose: Abstract classes are used to define common behavior and attributes for subclasses, while interfaces define a contract for classes to adhere to.

17) Define interface. How is it implemented in Python? 

Interface Definition:

An interface in programming is a blueprint for a class that defines a set of methods that must be implemented by any class that adheres to the interface. It specifies a contract that classes must follow, outlining the methods they should provide without specifying the implementation details. Interfaces help in achieving abstraction and enforcing a common structure among classes.

Implementation of Interface in Python:

In Python, interfaces are not natively supported as a distinct language feature like in some other programming languages (e.g., Java). However, interfaces can be emulated using abstract classes with all methods being abstract. The abc (Abstract Base Classes) module in Python provides the infrastructure for defining abstract classes and creating interfaces.

Steps to Implement an Interface in Python:

  1. Import the ABC and abstractmethod from the abc module:

    • The ABC class is used as a base class for defining abstract classes.
    • The abstractmethod decorator is used to define abstract methods within the abstract class.

  2. Define an Abstract Class with Abstract Methods:

    • Create an abstract class that inherits from ABC.
    • Define abstract methods within the abstract class using the @abstractmethod decorator.

  3. Implement the Interface in Concrete Classes:

    • Create concrete classes that inherit from the abstract class/interface.
    • Implement the abstract methods defined in the interface within the concrete classes.

Example of Interface Implementation in Python:

from abc import ABC, abstractmethod

# Define an interface (abstract class) named Printable
class Printable(ABC):
    @abstractmethod
    def print(self):
        pass

# Concrete class Document implementing the Printable interface
class Document(Printable):
    def print(self):
        print("Printing document...")

# Concrete class Image implementing the Printable interface
class Image(Printable):
    def print(self):
        print("Printing image...")

# Create objects of concrete classes and invoke the print method
doc = Document()
doc.print()

img = Image()
img.print()

In the example above, we define an interface Printable as an abstract class with an abstract method print. The concrete classes Document and Image implement the Printable interface by providing concrete implementations for the print method. Objects of the concrete classes are created and the print method is invoked, demonstrating the implementation of the interface in Python using abstract classes and method overriding.



18) What is an abstract method? Describe with an example. 

Abstract Method Definition:

An abstract method in object-oriented programming is a method declared in an abstract class or interface that does not have an implementation in the abstract class itself. Instead, the responsibility of providing the implementation for an abstract method lies with the subclasses that inherit from the abstract class or implement the interface. Abstract methods serve as placeholders that define a method's signature without specifying the actual implementation details.

Example of Abstract Method in Python:

from abc import ABC, abstractmethod

# Define an abstract class Shape with an abstract method area
class Shape(ABC):
    @abstractmethod
    def area(self):
        pass

# Concrete subclass Circle inheriting from Shape and implementing the area method
class Circle(Shape):
    def __init__(self, radius):
        self.radius = radius

    def area(self):
        return 3.14 * self.radius * self.radius

# Concrete subclass Rectangle inheriting from Shape and implementing the area method
class Rectangle(Shape):
    def __init__(self, length, width):
        self.length = length
        self.width = width

    def area(self):
        return self.length * self.width

# Create objects of concrete subclasses and calculate the area
circle = Circle(5)
rectangle = Rectangle(4, 6)

print("Area of the circle:", circle.area())
print("Area of the rectangle:", rectangle.area())

In the example above:

  • We define an abstract class Shape with an abstract method area using the @abstractmethod decorator from the abc module.
  • The Circle and Rectangle classes inherit from the Shape abstract class and provide concrete implementations for the area method.
  • The Circle class calculates the area of a circle based on the radius, while the Rectangle class calculates the area of a rectangle based on its length and width.
  • Objects of the concrete subclasses Circle and Rectangle are created, and the area method is called to calculate the area specific to each shape.



Short Answer :-

 1) State the access specifier of the following members of the Python class. 

a) Num

 b) _x 

c) def _show()

Ans-Given Members and their Access Specifiers:

a) Num: Public Access Specifier (No Prefix)

  • The member Num has no prefix, making it a public member that can be accessed from outside the class.

b) _x: Protected Access Specifier (Single Underscore Prefix _)

  • The member _x is prefixed with a single underscore, indicating that it is a protected member that can be accessed within the class and its subclasses.

c) def _show(): Protected Access Specifier (Single Underscore Prefix _)

  • The method _show() is defined with a single underscore prefix, making it a protected method that can be accessed within the class and its subclasses.

Therefore, based on the provided information, the access specifiers for the given members are as follows:

  • Num: Public
  • _x: Protected
  • def _show(): Protected

 2) Give the meaning of following method

 a) __del__

 b) __str__

 c) __init__ 

Ans- __del__: The __del__ method in Python is a special method used to define a destructor in a class. It is called when an object is about to be destroyed or garbage collected. This method can be used to perform clean-up activities before the object is removed from memory. The __del__ method is automatically invoked when the object is deleted using the del keyword or when the object goes out of scope.

b) __str__: The __str__ method in Python is a special method used to return a string representation of an object. When the str() function is called on an object or when the object is passed to print(), the __str__ method is automatically invoked to return a human-readable string representation of the object. By defining the __str__ method in a class, you can customize how the object is represented as a string.

c) __init__: The __init__ method in Python is a special method used as a constructor to initialize objects of a class. It is called automatically when a new instance of the class is created. The __init__ method is used to set up initial values for the object's attributes or perform any necessary initialization tasks. This method is essential for initializing the state of an object when it is created.

3) What type of inheritance is illustrated in the following Python code? Justify your answer.

class A(): 

 pass 

class B(A):

 pass class C(B) 

Pass 

Ans- The inheritance illustrated in the provided Python code is Multilevel Inheritance.

In Multilevel Inheritance, a derived class is created from another derived class. In this case:

  • Class B is derived from Class A (Single Inheritance)
  • Class C is derived from Class B

Therefore, the inheritance hierarchy in the code snippet is as follows:

  • Class A is the base class
  • Class B is derived from Class A
  • Class C is derived from Class B

This demonstrates a chain of inheritance where Class C inherits from Class B, which in turn inherits from Class A. This type of inheritance is known as Multilevel Inheritance.


4) What will be the output of the following code? Justify your answer? 

from abc import ABC, abstractmethod

 class Test(ABC): 

@abstractmethod

 def ex(self): None obj = Test()

Ans- The provided code defines a class Test that inherits from ABC (Abstract Base Class) and contains an abstract method ex decorated with @abstractmethod.

When an abstract method is defined in a class, any class that inherits from it must implement that abstract method. In this case, the Test class is not implementing the abstract method ex.

Attempting to create an object of the Test class without implementing the abstract method ex will result in an error. The code will raise a TypeError indicating that the abstract method ex in the Test class is not implemented.

Therefore, the output of the code will be a TypeError indicating that the abstract method ex in the Test class is not implemented.

 5) Give the syntax to implement the interface in Python class. 

In Python, interfaces are implemented using abstract classes that contain only abstract methods. The abc module in Python provides the necessary tools to define abstract classes and abstract methods. Here is the syntax to implement an interface in a Python class:

  1. Import the ABC (Abstract Base Class) and abstractmethod from the abc module:
from abc import ABC, abstractmethod
  1. Define an abstract class that inherits from ABC:
class InterfaceName(ABC):
  1. Define abstract methods within the abstract class using the @abstractmethod decorator:
@abstractmethod
def method_name(self):
    pass
  1. Implement the interface in a concrete class by inheriting from the abstract class:
class ConcreteClass(InterfaceName):
    def method_name(self):
        # Implement the method logic here
        pass

By following this syntax, you can create interfaces in Python using abstract classes and ensure that all methods defined in the interface are implemented in the concrete classes that inherit from it.

6) Create a Bus object that will inherit all of the variables and methods of the parent Vehicle class and display it.

To create a Bus object that inherits all variables and methods from a parent Vehicle class and display it, you can follow the below Python code example:

class Vehicle:
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year

    def display_info(self):
        print(f"Make: {self.make}, Model: {self.model}, Year: {self.year}")

class Bus(Vehicle):
    pass

# Creating a Bus object
bus = Bus("Volvo", "XYZ", 2022)

# Displaying the information using the inherited method
bus.display_info()

In this code:

  • The Vehicle class is defined with variables make, model, and year, along with a method display_info to display the information.
  • The Bus class is created by inheriting from the Vehicle class using class Bus(Vehicle): pass, which means the Bus class will inherit all variables and methods from the Vehicle class.
  • An instance of the Bus class named bus is created with specific values for make, model, and year.
  • The display_info method inherited from the Vehicle class is called on the bus object to display the information of the bus, which includes make, model, and year.


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