Three Simple Rules for Subtypes

Published: 01 January 1970
on channel: Dave Leeds

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Inheritance, declaration-site variance, and type projections are all based on three simple rules for subtypes. Once you understand those three rules, you can reason your way through inheritance and generic variance. In this video, we'll learn what those three rules are, and then see how they apply to a variety of Kotlin language features!

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📘 For further study: "Fundamentals of Object-Oriented Design in UML" by Meilir Page-Jones, published in 2000 by Dorset House Publishing and Addison-Wesley.

📚 Kotlin: An Illustrated Guide - Chapter 19: Generic Variance
Read the chapter online here: https://typealias.com/start/kotlin-va...

00:00 Introduction and Example Models
01:05 Three Simple Rules
02:42 Applied to Class Inheritance
04:08 Applied to Declaration-Site Variance
07:21 Applied to Use-Site Variance
12:36 Wrapping Up