Introduction

frozenlist.FrozenList is a list-like structure which implements collections.abc.MutableSequence. The list is mutable until FrozenList.freeze is called, after which list modifications raise RuntimeError:

>>> from frozenlist import FrozenList
>>> fl = FrozenList([17, 42])
>>> fl.append('spam')
>>> fl.append('Vikings')
>>> fl
<FrozenList(frozen=False, [17, 42, 'spam', 'Vikings'])>
>>> fl.freeze()
>>> fl
<FrozenList(frozen=True, [17, 42, 'spam', 'Vikings'])>
>>> fl.frozen
True
>>> fl.append("Monty")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "frozenlist/_frozenlist.pyx", line 97, in frozenlist._frozenlist.FrozenList.append
    self._check_frozen()
  File "frozenlist/_frozenlist.pyx", line 19, in frozenlist._frozenlist.FrozenList._check_frozen
    raise RuntimeError("Cannot modify frozen list.")
RuntimeError: Cannot modify frozen list.

FrozenList is also hashable, but only when frozen. Otherwise it also throws a RuntimeError:

>>> fl = FrozenList([17, 42, 'spam'])
>>> hash(fl)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "frozenlist/_frozenlist.pyx", line 111, in frozenlist._frozenlist.FrozenList.__hash__
    raise RuntimeError("Cannot hash unfrozen list.")
RuntimeError: Cannot hash unfrozen list.
>>> fl.freeze()
>>> hash(fl)
3713081631934410656
>>> dictionary = {fl: 'Vikings'} # frozen fl can be a dict key
>>> dictionary
{<FrozenList(frozen=True, [1, 2])>: 'Vikings'}

$ pip install frozenlist

Documentation

https://frozenlist.readthedocs.io/

Communication channels

aio-libs discourse group: https://aio-libs.discourse.group

Feel free to post your questions and ideas here.

gitter chat https://gitter.im/aio-libs/Lobby

Requirements

• Python >= 3.6

License

frozenlist is offered under the Apache 2 license.

Source code

The project is hosted on GitHub

Please file an issue in the bug tracker if you have found a bug or have some suggestions to improve the library.

1.2.0 (2021-10-16)

Features

• FrozenList now supports being used as a generic type as per PEP 585, e.g. frozen_int_list: FrozenList[int] (requires Python 3.9 or newer). #172

• Added support for Python 3.10. #227

• Started shipping platform-specific wheels with the musl tag targeting typical Alpine Linux runtimes. #227

• Started shipping platform-specific arm64 wheels for Apple Silicon. #227

1.1.1 (2020-11-14)

Bugfixes

• Provide x86 Windows wheels. #169

1.1.0 (2020-10-13)

Features

• Add support for hashing of a frozen list. #136

• Support Python 3.8 and 3.9.

• Provide wheels for aarch64, i686, ppc64le, s390x architectures on Linux as well as x86_64.

1.0.0 (2019-11-09)

Deprecations and Removals

• Dropped support for Python 3.5; only 3.6, 3.7 and 3.8 are supported going forward. #24