https://github.com/lexsca/rollback

Simple Python rollback mechanism
https://github.com/lexsca/rollback

Last synced: about 2 months ago
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Simple Python rollback mechanism

• Host: GitHub
• URL: https://github.com/lexsca/rollback
• Owner: lexsca
• License: mit
• Created: 2017-04-10T14:37:56.000Z (over 7 years ago)
• Default Branch: main
• Last Pushed: 2022-11-07T00:23:07.000Z (about 2 years ago)
• Last Synced: 2024-10-12T06:51:53.219Z (2 months ago)
• Language: Python
• Size: 29.3 KB
• Stars: 7
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

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README

        
Rollback

========

.. image:: https://github.com/lexsca/rollback/actions/workflows/checks.yml/badge.svg

    :target: https://github.com/lexsca/rollback/actions/workflows/checks.yml

.. image:: https://img.shields.io/pypi/v/rollback.svg

    :target: https://pypi.org/project/rollback/

.. image:: https://img.shields.io/pypi/pyversions/rollback.svg

    :target: https://pypi.org/project/rollback/

.. image:: https://img.shields.io/github/license/lexsca/rollback.svg

    :target: https://github.com/lexsca/rollback/blob/master/LICENSE

.. image:: https://img.shields.io/badge/code%20style-black-000000.svg

    :target: https://github.com/psf/black

|

This is a simple Pythonic mechanism for rolling back multiple operations in a predictable way, usable as a `context manager`_ or a standalone instance (see `Example usage`_). By default, errors are re-raised, but an explicit mode or call *must* be supplied to trigger a rollback. Valid modes are:

-  ``onError`` Boolean when ``True`` will roll back if an error is

   raised

-  ``onSuccess`` Boolean when ``True`` will roll back if an error is

   *not* raised

Both modes can be set to ``True`` to always rollback. A rollback can also be triggered manually by calling ``doRollback``.  Note that multiple calls to ``doRollback`` will only call the rollback steps once.

Errors can be supressed by setting ``raiseError`` to ``False``. Note that errors from rollback steps will not be surpressed, regardless of the ``raiseError`` setting.

If a rollback is triggered, each step is called in a last in, first out order (LIFO). That is, the most recently added step is called first, the first step is called last.

Compatibility

~~~~~~~~~~~~~

Rollback has no external dependencies and is regularly tested with all currently supported versions of cPython.

Installation

~~~~~~~~~~~~

Install from source:

::

  python setup.py install

Install from PyPI:

::

  pip install rollback

Example usage

~~~~~~~~~~~~~

.. code:: python

  from __future__ import print_function

  from rollback import Rollback

  # *always* rollback after exiting block, letting any error be re-raised

  with Rollback(onError=True, onSuccess=True) as rollback:

    print('do a1')

    rollback.addStep(print, 'undo a1')

    print('do a2')

    rollback.addStep(print, 'undo a2')

  # rollback *only* if *no* error is raised, letting any error be re-raised

  with Rollback(onSuccess=True) as rollback:

    print('do b1')

    rollback.addStep(print, 'undo b1')

    print('do b2')

    rollback.addStep(print, 'undo b2')

  # rollback manually

  with Rollback() as rollback:

    print('do c1')

    rollback.addStep(print, 'undo c1')

    print('do c2')

    rollback.addStep(print, 'undo c2')

    rollback.doRollback()

  # rollback *only* if an error is raised, suppressing the error

  with Rollback(onError=True, raiseError=False) as rollback:

    print('do d1')

    rollback.addStep(print, 'undo d1')

    print('do d2')

    rollback.addStep(print, 'undo d2')

    raise RuntimeError('this is not re-raised')

  # rollback *only* if an error is raised, letting the error be re-raised

  with Rollback(onError=True) as rollback:

    print('do e1')

    rollback.addStep(print, 'undo e1')

    print('do e2')

    rollback.addStep(print, 'undo e2')

    raise RuntimeError('this is re-raised')

Produces output:

::

  do a1

  do a2

  undo a2

  undo a1

  do b1

  do b2

  undo b2

  undo b1

  do c1

  do c2

  undo c2

  undo c1

  do d1

  do d2

  undo d2

  undo d1

  do e1

  do e2

  undo e2

  undo e1

  Traceback (most recent call last):

    File "example.py", line 41, in 

      raise RuntimeError('this is re-raised')

  RuntimeError: this is re-raised

.. _context manager: https://docs.python.org/3/reference/datamodel.html#with-statement-context-managers