A “frozen” dictionary for Python

Wow weird Mandela effect for me. I really remember this being a built and actually using it.

Perhaps you used the frozen dict implementation from the pip installable boltons library: https://boltons.readthedocs.io/en/latest/dictutils.html#bolt...

There was a previous PEP (in 2012) with the exact same title:

https://peps.python.org/pep-0416/

Also one in 2019 for a "frozenmap":

https://peps.python.org/pep-0603/

Perhaps immutabledict?

https://pypi.org/project/immutabledict/

You may be thinking of the `frozenset()` built in or the third party Python module [frozendict](https://pypi.org/project/frozendict/)?

Personally, I’ve been using a wrapper around `collections.namedtuple` as an underlying data structure to create frozen dictionaries when I’ve needed something like that for a project.

When you are making str -> Any dictionaries it's quite likely you're better off with dataclasses or namedtuples anyway.

That works if you're dealing with a known set of keys (i.e. what most statically-typed languages would call a struct). It falls down if you need something where the keys are unknowable until runtime, like a lookup table.

I do like dataclasses, though. I find them sneaking into my code more and more as time goes on. Having a declared set of properties is really useful, and it doesn't hurt either that they're syntactically nicer to use.