non-public name

In Python, a non-public name refers to the name of a variable, function, method, or attribute that is intended for internal use within a module or a class. These names are prefixed with an underscore (_) to signal that you shouldn’t access or modify them directly from outside the module or class.

Python doesn’t enforce strict access restrictions. Using a leading underscore is a naming convention that communicates the intended use of certain elements.

By marking a name as non-public, you indicate that it’s an implementation detail that can affect the module or class’s external interface be changed with.

Example

Here’s an example of non-public names in a Python class:

Python 
class DemoClass:
    def __init__(self, value):
        self._hidden_value = value  # Non-public attribute

    def get_value(self):
        return self._hidden_value

# Usage
demo = DemoClass(42)
demo.get_value()  # Output: 42
# Don't do this
print(demo._hidden_value)  # Outputs: 42
Single and Double Underscores in Python Names

Tutorial

Single and Double Underscores in Python Names

In this tutorial, you'll learn a few Python naming conventions involving single and double underscores (_). You'll learn how to use this character to differentiate between public and non-public names in APIs, write safe classes for subclassing purposes, avoid name clashes, and more.

intermediate best-practices python

For additional information on related topics, take a look at the following resources:

By Leodanis Pozo Ramos • Updated March 6, 2025 • Reviewed by Martin Breuss
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