Source code for ppb.features.twophase

A system for two phase updates: Update, and Commit.
from dataclasses import dataclass
from ppb.systemslib import System

__all__ = 'Commit',

[docs] @dataclass class Commit: """ Fired after Update. """
[docs] class TwoPhaseSystem(System): """ Produces the Commit event. """ def on_update(self, event, signal): signal(Commit())
[docs] class TwoPhaseMixin: """ Mixin to apply to objects to handle two phase updates. """ __staged_changes = None
[docs] def stage_changes(self, **kwargs): """ Stage changes for the next commit. These are just properties on the current object to update. """ if self.__staged_changes is None: self.__staged_changes = {} self.__staged_changes.update(kwargs)
[docs] def on_commit(self, event, signal): """ Commit changes previously staged. """ changes, self.__staged_changes = self.__staged_changes, {} if changes: for name, value in changes.items(): setattr(self, name, value)