A short talk about what is dependency injection and why you really need to learn and use it. After wards we should talk about it why you really need to learn and use it and con't chicken out...

Read about it:
https://en.wikipedia.org/wiki/Dependency_injection
https://www.martinfowler.com/articles/injection.html

Oh look there are free videos on youtube:
https://www.youtube.com/watch?v=IKD2-MAkXyQ
https://www.youtube.com/watch?v=0X1Ns2NRfks

https://2017.drupalcamp-frankfurt.de/node/168

https://www.drupal.org/u/kars-t