The Polymathic Engineer

The Polymathic Engineer

Software Design Principles That Matter

A tour over Open-Closed Principle, Dependency Injection, and Inversion of Control.

Franco Fernando's avatar
Franco Fernando
Jan 23, 2026
∙ Paid

Hi Friends,

Welcome to the 157th issue of the Polymathic Engineer.

Every software engineer has seen something like this happen: you write a feature, ship it to production, and everything works great. Then, a few weeks later, you get different requirements. You have to support a new use case, but you find out that your code is not ready.

You open the codeba…

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