Does Python Lack True Private Variables?

Python's "Private" Class Variables: A Cultural Norm

Python's class structure differs from Java's in that it does not mandate the declaration of instance variables within the constructor. Instead, instance variables can be initialized within the constructor or assigned later on. This flexibility raises the question: does Python lack the concept of private variables?

The Question: Why No Private Access Modifiers?

In Java, public, private, and protected access modifiers guard access to class variables. In Python, however, such access modifiers are absent. Bruce Eckel's Python Patterns manual illustrates that instance variables are simply assigned within the constructor, leaving the question of how to enforce encapsulation for sensitive data.

The Answer: Cultural Conventions and the __ Prefix

Python adheres to a cultural norm that discourages direct modification of other classes' instance or class variables. Unlike Java, Python encourages programmers to respect the privacy of other classes. While it is technically possible to modify private Java variables by directly editing the class source, this practice is strongly discouraged.

For those who wish to emulate private variables in Python, the __ prefix convention can be used. This prefix automatically mangles variable names, making them less visible outside their namespace. However, it is important to note that this is not a foolproof security measure and can be bypassed if necessary.

Additional Naming Conventions

Beyond the _ prefix, Python also encourages the use of the prefix for variables that should be used internally within a class or module. While such variables are technically accessible from outside their scope, it is considered good practice to refrain from modifying them.

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