Python for Finance, 3rd Edition

Chapter 7. Object-Oriented Programming

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The purpose of software engineering is to control complexity, not to create it.

Pamela Zave

Object-oriented programming (OOP) helps you structure code around the concepts you work with every day in finance: positions, portfolios, data loaders, and models. This chapter introduces Python’s class system in a pragmatic way so that, later in the book, code can encapsulate behavior cleanly instead of passing long lists of parameters between functions.

The chapter shows how to define simple classes in Python, work with attributes and methods, use special methods such as .__init__() and .__repr__(), and design small, testable objects for finance workflows. It shows how to create instances, model simple financial concepts such as positions and portfolios, separate responsibilities between data containers and behavior, and use basic inheritance when it genuinely simplifies code.

To follow along, you need a working python interpreter, familiarity with functions ...