# -*- coding: utf-8 -*-
from __future__ import absolute_import
from functools import partial
[docs]class HistoryManager(object):
"""Record a list of actions to be taken at a later time. Used to
implement context managers that allow temporary changes to a
:class:`~cobra.core.Model`.
"""
[docs] def __init__(self):
# self._history just acts as a stack
self._history = []
[docs] def __call__(self, operation):
"""Add the corresponding method to the history stack.
Parameters
----------
operation : `function`
A function to be called at a later time
"""
self._history.append(operation)
[docs] def reset(self):
"""Trigger executions for all items in the stack in reverse order"""
while self._history:
entry = self._history.pop()
entry()
[docs]def get_context(obj):
"""Search for a context manager"""
try:
return obj._contexts[-1]
except (AttributeError, IndexError):
pass
try:
return obj._model._contexts[-1]
except (AttributeError, IndexError):
pass
return None
[docs]def resettable(f):
"""A decorator to simplify the context management of simple object
attributes. Gets the value of the attribute prior to setting it, and stores
a function to set the value to the old value in the HistoryManager.
"""
def wrapper(self, new_value):
context = get_context(self)
if context:
old_value = getattr(self, f.__name__)
# Don't clutter the context with unchanged variables
if old_value == new_value:
return
context(partial(f, self, old_value))
f(self, new_value)
return wrapper