# -*- coding: utf-8 -*-
from typing import Any
from . import persistence
from .utils import SAVED_STATE_TYPE, AttributesDict, Optional
__all__ = ['ContextMixin']
[docs]class ContextMixin(persistence.Savable):
"""
Add a context to a Process. The contents of the context will be saved
in the instance state unlike standard instance variables.
"""
CONTEXT: str = '_context'
def __init__(self, *args: Any, **kwargs: Any):
super().__init__(*args, **kwargs) # type: ignore
self._context: Optional[AttributesDict] = AttributesDict()
@property
def ctx(self) -> Optional[AttributesDict]:
return self._context
[docs] def save_instance_state(
self, out_state: SAVED_STATE_TYPE, save_context: Optional[persistence.LoadSaveContext]
) -> None:
"""Add the instance state to ``out_state``.
.. important::
The instance state will contain a pointer to the ``ctx``,
and so should be deep copied or serialised before persisting.
"""
super().save_instance_state(out_state, save_context)
if self._context is not None:
out_state[self.CONTEXT] = self._context.__dict__
[docs] def load_instance_state(self, saved_state: SAVED_STATE_TYPE, load_context: persistence.LoadSaveContext) -> None:
super().load_instance_state(saved_state, load_context)
try:
self._context = AttributesDict(**saved_state[self.CONTEXT])
except KeyError:
pass
