I built this because I was bored. No real use case, no production target — just a C++17 exercise to shake off the rust and explore techniques I knew existed but had never actually used. What I didn't expect was how much the implementation taught me about things I thought I already understood. The Problem With Homogeneous Lists Every linked list tutorial shows you the same thing: a list of integers, or a list of strings. The node holds one type, the list holds nodes of that type, done. That works — until you want a single list to hold an integer, a float, a string, and a custom struct at the same time. Then the standard approach falls apart immediately, because the type is baked into the node at compile time. The question becomes: how do you build a node that doesn't care what it holds? The Polymorphic Base — The "Wow" Moment The answer is a polymorphic base class.…