Immutable Objects in Python

In Python, immutability offers a valuable mechanism for safeguarding data integrity. Creating immutable objects, however, presents certain challenges.

Overriding setattr

A common approach is to override the setattr method. However, this method is invoked even during the init process, making it unsuitable for creating immutable objects.

Subclassing a Tuple

Another strategy involves subclassing a tuple. This technique ensures immutability by directly overriding the new method. However, it exposes the tuple's underlying elements as self[0] and self[1], compromising their inaccessibility.

namedtuple as a Solution

For a simpler and more effective solution, consider employing Python's collections.namedtuple. This function creates a tuple-like type that resembles a class, featuring named attributes. Immutable = collections.namedtuple("Immutable", ["a", "b"])

This approach exhibits several advantages:

• Conciseness and ease of implementation
• Compatibility with pickle and copy
• Prevents attribute access via [0] etc.

Namedtuple's Implementation

Namedtuples are derived from tuples and utilize slots to ensure immutability. This is analogous to the subclassing approach, but with the additional benefit of named attributes.

Python 2.6 Compatibility

Namedtuples were introduced in Python 2.6, ensuring compatibility with older Python versions.

Conclusion

While various approaches exist for creating immutable objects in Python, namedtuples provide a convenient and effective solution that satisfies the need for immutability in Python programming.