https://github.com/matthiasdiener/constantdict
An immutable dict class for Python.
https://github.com/matthiasdiener/constantdict
dict frozen immutable python
Last synced: 7 months ago
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An immutable dict class for Python.
- Host: GitHub
- URL: https://github.com/matthiasdiener/constantdict
- Owner: matthiasdiener
- License: mit
- Created: 2024-01-21T04:30:43.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2025-03-03T22:39:40.000Z (7 months ago)
- Last Synced: 2025-03-17T04:06:49.066Z (7 months ago)
- Topics: dict, frozen, immutable, python
- Language: Python
- Homepage: https://matthiasdiener.github.io/constantdict/
- Size: 354 KB
- Stars: 5
- Watchers: 2
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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# constantdict
An immutable dictionary class for Python, implemented as a thin layer around Python's builtin `dict` class. It is often [faster than other immutable dictionary implementations](https://matthiasdiener.github.io/constantdict/comparison.html).
## Usage
Install this package with:
```
$ pip install constantdict
```
Usage example:
```python
from constantdict import constantdict
cd = constantdict({1: 2})
# constantdicts compare equal to dicts with the same items
assert cd == {1: 2}
# constantdicts are hashable, and their hashes are cached
print(hash(cd), cd)
# Attempting to modify a constantdict in-place raises an AttributeError
try:
# Similar for pop(), popitem(), clear(), and del
cd[4] = 12
except AttributeError:
pass
# Some methods return a mutated copy of a constantdict
cd_new = cd.setdefault(10, 5)
assert cd_new == {1: 2, 10: 5}
# Similar for set(), update(), delete(), discard()
# Performing multiple mutations can be faster via mutate()/finish()
cd_mut = cd.mutate() # cd_mut is a mutable copy of cd
cd_mut[42] = 0
del cd_mut[1]
cd_new2 = cd_mut.finish() # cd_new2 is an immutable version of cd_mut
assert cd_new2 == {42: 0}
```
Please also see the [documentation](https://matthiasdiener.github.io/constantdict),
as well as the examples in the `examples/` directory.
## References
### Other packages
- [immutabledict](https://github.com/corenting/immutabledict)
- [immutables](https://github.com/MagicStack/immutables)
- [pyrsistent](https://github.com/tobgu/pyrsistent)
- [frozendict (old)](https://github.com/slezica/python-frozendict)
- [frozendict (new)](https://github.com/Marco-Sulla/python-frozendict)
### PEPs
- [PEP 416](https://www.python.org/dev/peps/pep-0416/)
- [PEP 603](https://www.python.org/dev/peps/pep-0603/)
### Discussions
- [PEP 603: Adding a frozenmap type to collections](https://discuss.python.org/t/pep-603-adding-a-frozenmap-type-to-collections/2318)
## License
MIT License.