[rmbyrro]

> Don't use classes for information. Use regular data structures (dict, list, tuple, set) and use functions to manipulate them.

One problem is many of these datastructures are easy to mutate. When I need to ensure immutability to a dictionary, for instance - quite often - I can't avoid wrapping it in a class and setting up an interface to lock down mutation.

If Python had a way to declare immutable datastructure, similarly to Clojure, it would make life a lot easier...

[galoisscobi]

Frozen dataclass instances (https://docs.python.org/3/library/dataclasses.html#frozen-in...) might be of help.

[rmbyrro]

Wasn't aware of this feature in dataclasses, that can be helpful in a few cases, thanks for pointing out

[ciupicri]

> class types.MappingProxyType(mapping)

> Read-only proxy of a mapping. It provides a dynamic view on the mapping’s entries, which means that when the mapping changes, the view reflects these changes.

https://docs.python.org/3/library/types.html#types.MappingPr...

[rmbyrro]

This can be helpful in some cases, but it's precisely what I sometimes need to avoid, which is protecting a dictionary and having changes affecting only its own scope.

If function A passes a dict to function B, I would like:

1) Function A to keep the dict intact while function B can manipulate its content;

2) Function A can change the dict after passing to B, and B still keep the original copy, unaware of A's later changes.

One way of doing this is by deep copying dictionaries around, but it can easily become a big performance issue.

[ciupicri]

It sounds like what you really want is an efficient way of copying dictionaries, perhaps copy on write, something like the cowdict [1] project.

[1]: https://pypi.org/project/cowdict/