Pandas len() works due to dunder method in DataFrame class

Every Data Science library I want to use has a secret. I found it while studying OOP. ━━━━━━━━━━━━━━━━━━━━━━ When you write len(df) in Pandas — have you ever wondered why that works? len() is a Python built-in. df is a Pandas object. Why does Python even know what to do? ━━━━━━━━━━━━━━━━━━━━━━ Because Pandas defined len inside its DataFrame class. That's a dunder method. Double underscore before and after. Python calls them automatically — behind the scenes. ━━━━━━━━━━━━━━━━━━━━━━ When I was studying OOP, I kept skipping dunder methods. They looked weird. Unnecessary. I had no idea they were the reason Python "feels" so clean. ━━━━━━━━━━━━━━━━━━━━━━ ▶ len(df) → calls df.len() ▶ df + df2 → calls df.add(df2) ▶ print(df) → calls df.repr() Every time you use Pandas or NumPy naturally — a dunder method is running underneath. ━━━━━━━━━━━━━━━━━━━━━━ My Software Engineering brain finally connected the dots. This is just operator overloading. We did it in C++ and Java. Python just made it feel invisible. That "invisible" part is what makes Python powerful for Data Science. ━━━━━━━━━━━━━━━━━━━━━━ Senior Python developers — which dunder method do you think is the most underrated? Genuinely curious. SE → Data Science | OOP Series #1 | IUB #Python #OOP #DataScience #100DaysOfCode #SoftwareEngineering

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