Dependency Injection Lecture Notes

Introduction

• Welcome message
• Importance of Dependency Injection (DI)
• High demand and confusion around DI
• Requests to subscribe to YouTube channels: Techno Varsh White (technical tips) and Wellip (cooking recipes)

Basics to Understand Before DI

Prerequisites in C#:

• C# Basics: Loops, Conditional Statements, Arrays
• Methods: Understanding method creation and usage
• Properties: Knowledge of properties in C#
• Object-Oriented Programming Concepts: Classes, Objects
• Constructors: Well-understood constructors
• Inheritance: Understanding class inheritance
• Interfaces: Knowledge of C# interfaces
• Access Specifiers: Public, Private, Protected
• Abstraction: Familiarity with abstraction concepts

Tight Coupling vs. Loose Coupling

Tight Coupling

• Definition: Classes are highly dependent on one another
• Example: Group of classes where one class's change affects others
• Real-World Example: Car class depending on Engine and Brake classes
• Disadvantages:
  • Hard to maintain
  • Difficult to test
  • Single class with multiple responsibilities
  • High interdependency among classes

Loose Coupling

• Definition: Classes are independent of each other
• Advantages:
  • Easy to maintain
  • Easy to test
  • Promotes Single Responsibility Principle
  • Separation of concerns

Introduction to Dependency Injection (DI)

• Purpose: To avoid tight coupling
• Implementation: Using dependency injection achieves loose coupling
• Key Roles:
  • Client: Needs the service
  • Service: Provides the service
  • Injector: Mediates between clients and services
• Using Interfaces: Central to achieving DI; implement it through interfaces
• Impact in Code: Allows writing loosely coupled code

Types of Dependency Injection

• Constructor Injection: Using constructors to inject dependencies
• Property Injection: Using properties to inject dependencies
• Method Injection: Using methods to inject dependencies

Next Steps

• Practical implementation in the next lecture
• Importance of staying subscribed for upcoming practical videos

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