# Python 3.15 Preview: frozendict

DevFeed: [Python 3.15 Preview: frozendict](<https://devfeed.tech/articles/python-3-15-preview-frozendict-57604.md>)

Original publisher: [Read original article](<https://realpython.com/python315-frozendict/>)

Author: Bartosz Zaczyński

Published: 2026-09-21T14:00:00Z

Content type: tutorial

Language: en

Sources: [Real Python](<https://devfeed.tech/sources/real-python.md>)

Topics: [Python](<https://devfeed.tech/topics/python.md>), [Concurrency](<https://devfeed.tech/topics/concurrency.md>)

Tags: [cache](<https://devfeed.tech/tags/cache.md>), [immutability](<https://devfeed.tech/tags/immutability.md>), [mutation](<https://devfeed.tech/tags/mutation.md>), [preview](<https://devfeed.tech/tags/preview.md>), [python](<https://devfeed.tech/tags/python.md>), [threads](<https://devfeed.tech/tags/threads.md>), [tutorial](<https://devfeed.tech/tags/tutorial.md>)

## AI overview

A tutorial on Python 3.15's new built-in frozendict, an immutable mapping that can be hashable and used as a dictionary key, set member, or cache argument. It explains shallow immutability, hashability limits, rebinding with augmented assignment, and sharing mappings across threads.

## Source excerpt

Preview Python 3.15's frozendict: build immutable mappings you can hash, cache, and share across threads, and learn where the freeze stops.