Summary
Python’s private attributes use double underscores and name mangling to hide sensitive class data, ensuring it can only be accessed or modified through validated public methods for robust encapsulation.

General domain of usage
Banking and financial applications

Private attributes represent the strongest level of data protection in Python's encapsulation model. By using double underscores, they activate Python's **name mangling mechanism**, transforming sensitive attributes into nearly inaccessible identifiers. This provides robust protection against accidental interference and helps create secure, professional class designs.

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Although private attributes can technically be accessed through their mangled names, doing so violates encapsulation and should never be used in production code.

Note

A private attribute like `__balance` in `BankAccount` is automatically renamed to `_BankAccount__balance` through name mangling. This makes it harder to access directly and discourages external use.

Private attributes secure **sensitive state** and ensure interaction only through **validated public methods**. In classes like **Wallet** or **BankAccount**, data such as balance, PIN, and transaction history stay private, while methods like `deposit()`, `withdraw()`, and `authenticate()` enforce rules and maintain security.

What is the main purpose of private attributes in Python?

Learn how to build clean, secure, and scalable applications with Object-Oriented Programming in Python. Cover the fundamentals of classes and objects, then moves into advanced concepts such as inheritance, composition, polymorphism, and encapsulation. With clear explanations and practical examples, you'll develop the ability to design Python programs that are powerful, maintainable, and ready for real-world use.

Learn the core building blocks of object-oriented programming in Python. This section covers classes, objects, methods, and variables, giving you a solid base to understand how OOP organizes and structures code.

Explore how classes can share and extend functionality. You'll learn different inheritance patterns, from simple hierarchies to multiple inheritance and abstract classes, and see how they enable code reuse and scalability.

Discover how to build flexible systems by combining objects. Instead of relying only on inheritance, you'll see how composition lets you assemble behaviors in a modular, adaptable way.

Understand how different objects can share a common interface while behaving in their own way. This section shows how method overriding, interfaces, and protocols make your code more dynamic and reusable.

Learn how to safeguard internal data and control access to class attributes. You'll explore private attributes, getters and setters, and data-hiding techniques that keep your classes secure and maintainable.

Defining Private Attributes

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Defining Private Attributes