Python Classes and Object-Oriented Concepts

Overview

• Introduction to creating and using classes in Python.
• Object-oriented concepts covered in multiple videos:
  • Basics of creating and instantiating classes.
  • Inheritance.
  • Class and instance variables.
  • Static methods and class methods.

Why Use Classes?

• Classes are used across modern programming languages.
• Benefits include:
  • Logical grouping of data and functions.
  • Easy reuse and building upon functionalities.
• Terms:
  • Attributes: Data associated with a class.
  • Methods: Functions associated with a class.

Creating a Simple Employee Class

• Use case for classes: Representing employees in code.
• Example attributes for employees: name, email, pay.
• Class creation syntax: class Employee:.
• Empty class initialization using pass statement.

Class vs. Instance of a Class

• Class is a blueprint for creating instances.
• Each instance of a class is unique.
• Example: employee1 = Employee() and employee2 = Employee().

Instance Variables

• Instance variables store unique data for each instance.
• Manual initialization example:
  • Setting attributes for employee1 and employee2 manually.

Using the __init__ Method

• To automate attribute assignments, use the __init__ method (constructor).
• Syntax:

  def __init__(self, first, last, pay):
  

• Set instance variables within __init__ using self keyword:
  • self.first = first
  • self.last = last
  • self.pay = pay
  • Construct email using first and last names.

Creating Instances

• When creating instances, pass arguments to __init__ method:

  employee1 = Employee('Corey', 'Schaefer', 50000)
  employee2 = Employee('Test', 'User', 60000)
  

Methods in Classes

• To perform actions, add methods to the class.
• Example: Creating a method to display the full name:

  def full_name(self):
      return f'{self.first} {self.last}'
  

• Call the method using parentheses: employee1.full_name().

Common Mistakes

• Forgetting to include the self argument in methods will raise a TypeError.
• Example error: Method without self does not recognize instance.

Calling Methods

• Methods can be called on instances or directly on the class (but require instance to pass):

  Employee.full_name(employee1)
  

• Automatic passing of instance when calling from an instance.

Summary of the Video

• Covered:
  • Creation of simple classes.
  • Difference between classes and instances.
  • Initialization of attributes and creation of methods.
• Upcoming topics include class variables and advanced concepts.

Engagement

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