.. image:: https://github.com/aio-libs/frozenlist/workflows/CI/badge.svg :target: https://github.com/aio-libs/frozenlist/actions :alt: GitHub status for master branch

.. image:: https://codecov.io/gh/aio-libs/frozenlist/branch/master/graph/badge.svg?flag=pytest :target: https://codecov.io/gh/aio-libs/frozenlist?flags[]=pytest :alt: codecov.io status for master branch

.. image:: https://img.shields.io/pypi/v/frozenlist.svg?logo=Python&logoColor=white :target: https://pypi.org/project/frozenlist :alt: frozenlist @ PyPI

.. image:: https://readthedocs.org/projects/frozenlist/badge/?version=latest :target: https://frozenlist.aio-libs.org :alt: Read The Docs build status badge

.. image:: https://img.shields.io/matrix/aio-libs:matrix.org?label=Discuss%20on%20Matrix%20at%20%23aio-libs%3Amatrix.org&logo=matrix&server_fqdn=matrix.org&style=flat :target: https://matrix.to/#/%23aio-libs:matrix.org :alt: Matrix Room — #aio-libs:matrix.org

.. image:: https://img.shields.io/matrix/aio-libs-space:matrix.org?label=Discuss%20on%20Matrix%20at%20%23aio-libs-space%3Amatrix.org&logo=matrix&server_fqdn=matrix.org&style=flat :target: https://matrix.to/#/%23aio-libs-space:matrix.org :alt: Matrix Space — #aio-libs-space:matrix.org

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 "", line 1, in 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 "", line 1, in 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

https://frozenlist.aio-libs.org

We have a Matrix Space #aio-libs-space:matrix.org <https://matrix.to/#/%23aio-libs-space:matrix.org>_ which is also accessible via Gitter.

frozenlist is offered under the Apache 2 license.

The project is hosted on GitHub_

Please file an issue in the bug tracker <https://github.com/aio-libs/frozenlist/issues>_ if you have found a bug or have some suggestions to improve the library.

.. _GitHub: https://github.com/aio-libs/frozenlist