https://nalar.dev/tags/immutability/ Recent content in Immutability on Nalar Hugo en-us Wed, 09 Sep 2026 00:00:00 +0700 https://nalar.dev/update-immutable-records-with-copy-replace/ Wed, 09 Sep 2026 00:00:00 +0700 https://nalar.dev/update-immutable-records-with-copy-replace/ <p>I like immutable value objects because they make state changes explicit. The awkward part is that Python has historically offered several different ways to create a slightly modified version of one.</p> <p>A dataclass has <code>dataclasses.replace()</code>. A named tuple has <code>_replace()</code>. A custom class usually needs its own helper. The operations are conceptually similar, but generic code has no single interface to target.</p> <p>Python 3.13 adds <code>copy.replace()</code> to close that gap. It creates a new object of the same type while replacing selected fields, and it works with dataclasses, named tuples, and classes that implement <code>__replace__()</code>.</p>