accretive

.. vim: set fileencoding=utf-8: .. -- coding: utf-8 -- .. +--------------------------------------------------------------------------+ | | | Licensed under the Apache License, Version 2.0 (the "License"); | | you may not use this file except in compliance with the License. | | You may obtain a copy of the License at | | | | http://www.apache.org/licenses/LICENSE-2.0 | | | | Unless required by applicable law or agreed to in writing, software | | distributed under the License is distributed on an "AS IS" BASIS, | | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | | See the License for the specific language governing permissions and | | limitations under the License. | | | +--------------------------------------------------------------------------+

                               accretive

.. image:: https://img.shields.io/pypi/v/accretive :alt: Package Version :target: https://pypi.org/project/accretive/

.. image:: https://img.shields.io/pypi/status/accretive :alt: PyPI - Status :target: https://pypi.org/project/accretive/

.. image:: https://github.com/emcd/python-accretive/actions/workflows/tester.yaml/badge.svg?branch=master&event=push :alt: Tests Status :target: https://github.com/emcd/python-accretive/actions/workflows/tester.yaml

.. image:: https://emcd.github.io/python-accretive/coverage.svg :alt: Code Coverage Percentage :target: https://github.com/emcd/python-accretive/actions/workflows/tester.yaml

.. image:: https://img.shields.io/github/license/emcd/python-accretive :alt: Project License :target: https://github.com/emcd/python-accretive/blob/master/LICENSE.txt

.. image:: https://img.shields.io/pypi/pyversions/accretive :alt: Python Versions :target: https://pypi.org/project/accretive/

🌌 A Python library package which provides accretive data structures - collections which can grow but never shrink.

Key Features ⭐

• 📖 Accretive Dictionary: Like a regular dict <https://docs.python.org/3/library/stdtypes.html#dict>_, but entries cannot be modified or removed once added. Also has variants with defaults and validation.
• 🗃️ Accretive Namespace: Similar to SimpleNamespace <https://docs.python.org/3/library/types.html#types.SimpleNamespace>_, but attributes become immutable after assignment.
• 🧱 Additional Types: Classes (including abstract base classes), modules, and objects with accretive behavior.
• 🏗️ Flexible Initialization: Support for unprotected attributes during initialization; useful for compatibility with class decorators, such as dataclasses <https://docs.python.org/3/library/dataclasses.html#dataclasses.dataclass>_.
• 🔓 Flexible Mutability: Support for declaring specific attributes as mutable, enabling selective modification while maintaining immutability for other attributes.

Installation 📦

Method: Install Python Package

Install via uv <https://github.com/astral-sh/uv/blob/main/README.md>_ pip command:

::

uv pip install accretive

Or, install via pip:

::

pip install accretive

Note on Immutability 📢

Enforcement of immutability is quite difficult in Python. While this library encourages immutability by default, it can be circumvented by anyone who has intermediate knowledge of Python machinery and who is determined to circumvent the immutability. Use the library in the spirit of making programs safer, but understand that it cannot truly prevent unwanted state tampering.

Examples 💡

Accretive Namespaces 🗃️

An accretive namespace, similar to types.SimpleNamespace, is available. This namespace can be initialized from multiple iterables and from keyword arguments. (Keyword arguments shown below; see documentation for additional forms of initialization.)

from accretive import Namespace ns = Namespace( apples = 12, bananas = 6 ) ns.cherries = 42 # ✅ Allows new attributes. ns.apples = 14 # ❌ Attempted reassignment raises error. Traceback (most recent call last): ... accretive.exceptions.AttributeImmutability: Could not assign or delete existing attribute 'apples'. del ns.apples # ❌ Attempted deletion raises error. Traceback (most recent call last): ... accretive.exceptions.AttributeImmutability: Could not assign or delete existing attribute 'apples'. ns accretive.namespaces.Namespace( apples = 12, bananas = 6, cherries = 42 )

Accretive Dictionaries 📖

An accretive dictionary, similar to dict, is available. This dictionary can be initialized from multiple iterables and from keyword arguments. (Keyword arguments shown below; see documentation for additional forms of initialization.)

from accretive import Dictionary dct = Dictionary( apples = 12, bananas = 6 ) dct[ 'cherries' ] = 42 # ✅ Allows new entries. dct.update( blueberries = 96, strawberries = 24 ) accretive.dictionaries.Dictionary( {'apples': 12, 'bananas': 6, 'cherries': 42, 'blueberries': 96, 'strawberries': 24} ) dct[ 'bananas' ] = 11 # ❌ Attempted alteration raises error. Traceback (most recent call last): ... accretive.exceptions.EntryImmutability: Could not alter or remove existing entry for 'bananas'. del dct[ 'bananas' ] # ❌ Attempted removal raises error. Traceback (most recent call last): ... accretive.exceptions.EntryImmutability: Could not alter or remove existing entry for 'bananas'. dct accretive.dictionaries.Dictionary( {'apples': 12, 'bananas': 6, 'cherries': 42, 'blueberries': 96, 'strawberries': 24} )

Accretive Objects 🧱

The accretive decorator can be applied to any class to make its instances enforce attribute immutability after assignment.

from accretive import with_standard_behaviors @with_standard_behaviors ... class Config: ... def init( self, debug = False ): ... self.debug = debug ... config = Config( debug = True ) config.verbose = True # ✅ Allows new attributes config.debug = False # ❌ Attempted reassignment raises error Traceback (most recent call last): ... accretive.exceptions.AttributeImmutability: Could not assign or delete existing attribute 'debug'.

Use Cases 🎯

• 📝 Configuration Registries: Registries which can accumulate entries but never remove them, thereby guaranteeing sticky state.
• 🔌 Plugin Systems: Register extensions which are then guaranteed to be available from the time of registration to the end of the process.
• 🔒 Immutable Collections: Many scenarios requiring grow-only collections with immutability guarantees.

Contribution 🤝

Contribution to this project is welcome! However, it must follow the code of conduct <https://emcd.github.io/python-project-common/stable/sphinx-html/common/conduct.html>_ for the project.

Please file bug reports and feature requests in the issue tracker <https://github.com/emcd/python-accretive/issues>_ or submit pull requests <https://github.com/emcd/python-accretive/pulls>_ to improve the source code or documentation.

For development guidance and standards, please see the development guide <https://emcd.github.io/python-accretive/stable/sphinx-html/contribution.html#development>_.

Additional Indicia

.. image:: https://img.shields.io/github/last-commit/emcd/python-accretive :alt: GitHub last commit :target: https://github.com/emcd/python-accretive

.. image:: https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/copier-org/copier/master/img/badge/badge-grayscale-inverted-border-orange.json :alt: Copier :target: https://github.com/copier-org/copier

.. image:: https://img.shields.io/badge/%F0%9F%A5%9A-Hatch-4051b5.svg :alt: Hatch :target: https://github.com/pypa/hatch

.. image:: https://img.shields.io/badge/pre--commit-enabled-brightgreen?logo=pre-commit :alt: pre-commit :target: https://github.com/pre-commit/pre-commit

.. image:: https://microsoft.github.io/pyright/img/pyright_badge.svg :alt: Pyright :target: https://microsoft.github.io/pyright

.. image:: https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/ruff/main/assets/badge/v2.json :alt: Ruff :target: https://github.com/astral-sh/ruff

.. image:: https://img.shields.io/pypi/implementation/accretive :alt: PyPI - Implementation :target: https://pypi.org/project/accretive/

.. image:: https://img.shields.io/pypi/wheel/accretive :alt: PyPI - Wheel :target: https://pypi.org/project/accretive/

Other Projects by This Author 🌟

• python-absence <https://github.com/emcd/python-absence>_ (absence <https://pypi.org/project/absence/>_ on PyPI)

  🕳️ A Python library package which provides a sentinel for absent values - a falsey, immutable singleton that represents the absence of a value in contexts where None or False may be valid values.

• python-classcore <https://github.com/emcd/python-classcore>_ (classcore <https://pypi.org/project/classcore/>_ on PyPI)

  🏭 A Python library package which provides foundational class factories and decorators for providing classes with attributes immutability and concealment and other custom behaviors.

• python-dynadoc <https://github.com/emcd/python-dynadoc>_ (dynadoc <https://pypi.org/project/dynadoc/>_ on PyPI)

  📝 A Python library package which bridges the gap between rich annotations and automatic documentation generation with configurable renderers and support for reusable fragments.

• python-falsifier <https://github.com/emcd/python-falsifier>_ (falsifier <https://pypi.org/project/falsifier/>_ on PyPI)

  🎭 A very simple Python library package which provides a base class for falsey objects - objects that evaluate to False in boolean contexts.

• python-frigid <https://github.com/emcd/python-frigid>_ (frigid <https://pypi.org/project/frigid/>_ on PyPI)

  🔒 A Python library package which provides immutable data structures - collections which cannot be modified after creation.

• python-icecream-truck <https://github.com/emcd/python-icecream-truck>_ (icecream-truck <https://pypi.org/project/icecream-truck/>_ on PyPI)

  🍦 Flavorful Debugging - A Python library which enhances the powerful and well-known icecream package with flavored traces, configuration hierarchies, customized outputs, ready-made recipes, and more.

• python-mimeogram <https://github.com/emcd/python-mimeogram>_ (mimeogram <https://pypi.org/project/mimeogram/>_ on PyPI)

  📨 A command-line tool for exchanging collections of files with Large Language Models - bundle multiple files into a single clipboard-ready document while preserving directory structure and metadata... good for code reviews, project sharing, and LLM interactions.