What's the difference between dependency inversion and dependency injection? Dependency injection is a design pattern that splits creation of objects from their usage. Dependency inversion is a design principle that promotes using abstract classes and interfaces to better separate code. Watch this video to see a few practical examples in Python, and how these concepts help you write nice code that's easy to test.

The code I worked on in this example is available here: https://github.com/ArjanCodes/2021-de....

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A few interesting links to articles and books:
- Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides: https://amzn.to/3jllgyH
- Principles of Package Design: Creating Reusable Software Components by Matthias Noback: https://amzn.to/2NETK3l
- Clean Code: A Handbook of Agile Software Craftsmanship by Robert Martin: https://amzn.to/3qVZgNs
- The original Design Principles and Design Patterns article by Robert Martin: https://fi.ort.edu.uy/innovaportal/fi...

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🔖 Chapters:
0:00 Intro
0:20 What is a dependency?
1:10 Dependency injection
1:36 Dependency inversion
2:03 Example code
3:22 Example unit tests
5:32 Issues with testing
6:37 Applying dependency injection
8:35 Writing the unit tests
11:20 Applying dependency inversion
12:51 Coverage reports and abstract classes
14:16 The power of dependency inversion
14:49 Adding another authorizer
15:44 Adding tests for the Robot authorizer
17:10 Summary

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