Outline

1. Inversion of Control
2. Dependency Injection
3. django-di

What is Inversion of Control?

The idea that a library calls your code instead of you calling a library (framework).

Don't call us, we'll call you (Hollywood's Law)

What is Inversion of Control?

Instead of

your code => library

with IoC

your code <= library (inverted)

Examples of Inversion of Control

• Tkinter
• unittest (setUp, tearDown, ...)
• Django views (called by Django framework)

What is Dependency Injection?

An IoC technique for separating construction from use.

We pass a class its dependencies instead of creating them within the class.

$10 word for a 5𝇍 concept

What are some benefits of DI?

• Decreased coupling
• Testability
• Composability ("has a", not "is a")

Auto Dependency Injection

Taking things a step further with DI Containers

References

• https://martinfowler.com/articles/injection.html
• https://martinfowler.com/bliki/InversionOfControl.html