Functions as Objects

In Python, functions are objects like any other value. You can store them in variables, pass them to other functions, return them from functions, and even store them in data structures. This concept is called "first-class functions." This idea might seem abstract at first, but it's fundamental to Python's flexibility. Understanding it unlocks powerful patterns like callbacks, strategies, and the decorator pattern we'll explore later. Functions Are Values A function name without parentheses refers to the function object itself, not the result of calling it. This distinction is crucial: Functions in Collections Since functions are objects, you can store them in lists, dictionaries, or any other data structure. This enables powerful patterns: This pattern is sometimes called a "dispatch table

About This Interactive Section

This section is part of the Functional Programming: Advanced lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

How DataDriven Lessons Work

DataDriven combines four interview rounds (SQL, Python, Data Modeling, Pipeline Architecture) with adaptive difficulty and spaced repetition. Easy problems get harder as you improve. Weak concepts resurface until you master them. Your readiness score tracks progress across every topic interviewers test. Every lesson section ends with problems you solve by writing and running real code, not by picking multiple-choice answers.