How Does Python Handle Constants?

Python's Approach to Constant Creation

While Java employs the "static final" keyword to define constants, Python takes a different approach. Constant variables are not natively supported in Python's syntax.

Acknowledging Constants through Naming Convention

To indicate a variable's constant status, programmers typically resort to naming it in uppercase. This convention helps alert other developers to its intended immutability.

Example:

CONST_NAME = "Name"

Enforcing Constants (Optional)

For further code protection, Alex Martelli proposes a method in "Constants in Python" that raises exceptions upon altering constant values. However, this approach is not widely used in practical scenarios.

Python 3.8: Introducing a Closer Equivalent

Python 3.8 introduces the typing.Final variable annotation. While this informs static type checkers (e.g., mypy) that a variable should remain unchanged, it does not actually prevent reassignment.

Example:

from typing import Final

a: Final[int] = 1

# Executes smoothly, but mypy will flag an error if used:
a = 2

Despite its similarity to Java's "final" keyword, typing.Final does not enforce constant nature, leaving Python without a true constant declaration mechanism.

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