Hacker News is a community-driven platform for sharing and discussing technology news, startups, and programming-related topics. Through user submissions and comments, Hacker News offers insights into emerging technology trends, industry developments, and entrepreneurial ventures. Readers can participate in discussions, share their insights, and stay informed about the latest advancements in technology and innovation.

Hacker News

Explores the historical origins and context of the "favor composition over inheritance" principle from the Gang of Four's Design Patterns book. Examines the three-page discussion that led to this aphorism, including the white-box versus black-box reuse distinction, language-specific considerations in Smalltalk and Java, and the compile-time versus runtime trade-offs. References Barbara Liskov's earlier work on subtypes and polymorphism, highlighting that composition and inheritance aren't the only options—first-class procedures offer a third alternative that the simplified aphorism overlooks.

When did people favor composition over inheritance?

<ol>
<li>It’s simpler to understand, read, and write</li>
<li>It’s quite enough for most programs</li>
<li>It’s harder to abuse, unlike OOP inheritance as we have it</li>
<li>Its easier on the compiler (for maintenance, optimizations, etc)</li>
<li>People got tired of objects having great-great-grandparents with a bunch of method overrides along the way</li>
<li>OOP was abuses enough that composition became more attractive to program in</li>
</ol>
<p>That being said, OOP languages technically support composition, it’s just that it’s easy to abuse inheritance and method overloading in them.</p>


<p>I’ve always favored composition over inheritance, significantly simpler mental models in addition to being way more flexible.</p>
