Beginner tutorial on OOP and Classes in Python

Understanding Classes in Python:

Classes in Python allow you to create blueprints for objects. These objects can have attributes (characteristics) and methods (functions) associated with them. By using classes, you can organize your code more effectively, encapsulate data and functionality, and create reusable components.

Example: Student Management System

Suppose we want to create a student management system where we can store information about students, such as their name, age, and grades, and perform actions like adding new students, calculating average grades, and displaying student information.

Step 1: Creating the Student Class

class Student:
    def __init__(self, name, age):
        self.name = name
        self.age = age
        self.grades = []
    def add_grade(self, grade):
        self.grades.append(grade)
    def calculate_average_grade(self):
        if len(self.grades) == 0:
            return 0
        else:
            return sum(self.grades) / len(self.grades)
    def display_info(self):
        print(f"Name: {self.name}, Age: {self.age}, Grades: {self.grades}, Average Grade: {self.calculate_average_grade()}")

In this class:

• We define the Student class with attributes name, age, and grades.
• We define methods add_grade, calculate_average_grade, and display_info to perform actions related to students.

Step 2: Creating Students and Performing Actions

# Create students
student1 = Student("Alice", 18)
student2 = Student("Bob", 17)
# Add grades
student1.add_grade(85)
student1.add_grade(90)
student2.add_grade(75)
student2.add_grade(80)
student2.add_grade(95)
# Display student information
student1.display_info()
student2.display_info()

In this step:

• We create instances of the Student class representing different students.
• We add grades to these students using the add_grade method.
• We display information about the students, including their name, age, grades, and average grade, using the display_info method.

Classes in Python provide a way to model real-world entities and their behaviors. In this example, we created a Student class to represent students and demonstrated how to create instances of this class, add grades, and display student information.

By using classes, you can create modular, reusable components, making your code more organized and easier to maintain. This example provides a basic introduction to classes in Python, but there's much more you can do with classes, such as inheritance, polymorphism, and encapsulation, which we can explore further in future tutorials.

Let's extend the student management system example by introducing a Course class to manage courses and enroll students in them.

Step 3: Creating the Course Class

class Course:
    def __init__(self, course_name, max_students):
        self.course_name = course_name
        self.max_students = max_students
        self.students_enrolled = []
    def enroll_student(self, student):
        if len(self.students_enrolled) < self.max_students:
            self.students_enrolled.append(student)
            print(f"{student.name} enrolled in {self.course_name} course.")
        else:
            print(f"Cannot enroll {student.name}. Course is full.")
    def display_students(self):
        print(f"Students enrolled in {self.course_name} course:")
        for student in self.students_enrolled:
            print(student.name)

# Create courses
math_course = Course("Math", 3)
english_course = Course("English", 2)
# Enroll students in courses
math_course.enroll_student(student1)
math_course.enroll_student(student2)
english_course.enroll_student(student1)
english_course.enroll_student(student2)
# Display students enrolled in each course
math_course.display_students()
english_course.display_students()