mutable-object

DataFunSummit

Apr 7, 2022 · Fundamentals

Common Pitfalls When Using Python Lists: Mutability, Function Arguments, Class Initialization, and Method Return Values

This article explains why Python lists are mutable objects, illustrates how passing them to functions or using them as default class arguments can cause unexpected side‑effects, and warns that methods like append and extend modify the list in‑place without returning a new value.