Design Principle (2): Inversion of Control (IoC) Principle

Note: this article is published on 07/01/2024.

This series of articles will discuss Software Design Principles.

A - Introduction

Inversion of Control is a principle in software engineering which transfers the control of objects or portions of a program to a container or framework. We most often use it in the context of object-oriented programming.

In contrast with traditional programming, in which our custom code makes calls to a library, IoC enables a framework to take control of the flow of a program and make calls to our custom code. To enable this, frameworks use abstractions with additional behavior built in.

The content of this article:

A - Introduction
B - Inversion of Control
- What is Dependency?
- Dependency Management
- Inversion of Control (IoC)
- IoC Container or DI Container
- What is a DI Container?
- IoC Implementation
C - Inversion of Control Principle
- IoC, DIP, DI and IoC
- Step 1: Inversion of Control
- Step 2: Dependency Inversion Principle
- Step 3: Dependency Injection
- Step 4: IoC Container
- Lifecycle of the DI Containers
- Open Source Containers for .NET
D - IoC implementation
E - Dependency Injection implementation
- DI Factors
- DI using Constructor, Method or Property

B - Inversion of Control

C - Inversion of Control Principle

Introduction IoC, DIP, DI and IoC Container

Step 1: Inversion of Control

Step 2: Dependency Inversion Principle

Step 3: Dependency Injection

Step 4: IoC Containers

Lifecycle of the DI Containers
- Register: The container must know which dependency to instantiate when it encounters a particular type. This process is called registration. Basically, it must include some way to register type-mapping.
- Resolve: When using the IoC container, we don't need to create objects manually. The container does it for us. This is called resolution. The container must include some methods to resolve the specified type; the container creates an object of the specified type, injects the required dependencies if any and returns the object.
- Dispose: The container must manage the lifetime of the dependent objects. Most IoC containers include different lifetimemanagers to manage an object's lifecycle and dispose it.
Containers for .NET
- Unity
- StructureMap
- Castle Windsor
- Ninject
- Autofac
- DryIoc
- Simple Injector
- Light Inject
- .NET Core default DI Container

A - Introduction

B - Inversion of Control

C - Inversion of Control Principle

D - IoC implementation

E - Dependency Injection implementation