##############################################################################
#
# Copyright (c) 2001, 2002 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE
#
##############################################################################
"""Python implementation of persistent base types."""
from collections import UserDict as IterableUserDict
import persistent
class default:
def __init__(self, func):
self.func = func
def __get__(self, inst, class_):
if inst is None:
return self
return self.func(inst)
[docs]
class PersistentMapping(IterableUserDict, persistent.Persistent):
"""A persistent wrapper for mapping objects.
This class allows wrapping of mapping objects so that object
changes are registered. As a side effect, mapping objects may be
subclassed.
A subclass of PersistentMapping or any code that adds new
attributes should not create an attribute named _container. This
is reserved for backwards compatibility reasons.
"""
# UserDict provides all of the mapping behavior. The
# PersistentMapping class is responsible marking the persistent
# state as changed when a method actually changes the state. At
# the mapping API evolves, we may need to add more methods here.
__super_delitem = IterableUserDict.__delitem__
__super_setitem = IterableUserDict.__setitem__
__super_clear = IterableUserDict.clear
__super_update = IterableUserDict.update
__super_setdefault = IterableUserDict.setdefault
__super_pop = IterableUserDict.pop
__super_popitem = IterableUserDict.popitem
# Be sure to make a deep copy of our ``data`` (See PersistentList.) See
# https://github.com/python/cpython/commit/3645d29a1dc2102fdb0f5f0c0129ff2295bcd768
# This was fixed in CPython 3.7.4, but we can't rely on that because it
# doesn't handle our old ``_container`` appropriately (it goes directly to
# ``self.__dict__``, bypassing the descriptor). The code here was initially
# based on the version found in 3.7.4.
def __copy__(self):
inst = self.__class__.__new__(self.__class__)
inst.__dict__.update(self.__dict__)
# Create a copy and avoid triggering descriptors
if '_container' in inst.__dict__:
# BWC for ZODB < 3.3.
data = inst.__dict__.pop('_container')
else:
data = inst.__dict__['data']
inst.__dict__["data"] = data.copy()
return inst
def __delitem__(self, key):
self.__super_delitem(key)
self._p_changed = 1
def __setitem__(self, key, v):
self.__super_setitem(key, v)
self._p_changed = 1
[docs]
def clear(self):
"""
Remove all data from this dictionary.
.. versionchanged:: 4.5.2
If there was nothing to remove, this object is no
longer marked as modified.
"""
# Historically this method always marked ourself as changed,
# so if there was a _container it was persisted as data. We want
# to preserve that, even if we won't make any modifications otherwise.
needs_changed = '_container' in self.__dict__ or bool(self)
# Python 2 implements this by directly calling self.data.clear(),
# but Python 3 does so by repeatedly calling self.popitem()
self.__super_clear()
if needs_changed:
self._p_changed = 1
[docs]
def update(self, *args, **kwargs):
"""
D.update([E, ]**F) -> None.
.. versionchanged:: 4.5.2
Now accepts arbitrary keyword arguments. In the special case
of a keyword argument named ``b`` that is a dictionary,
the behaviour will change.
"""
self.__super_update(*args, **kwargs)
self._p_changed = 1
[docs]
def setdefault(self, key, default=None):
# We could inline all of UserDict's implementation into the
# method here, but I'd rather not depend at all on the
# implementation in UserDict (simple as it is).
if key not in self.data:
self._p_changed = 1
return self.__super_setdefault(key, default=default)
[docs]
def pop(self, key, *args, **kwargs):
self._p_changed = 1
return self.__super_pop(key, *args, **kwargs)
[docs]
def popitem(self):
"""
Remove an item.
.. versionchanged:: 4.5.2
No longer marks this object as modified if it was empty
and an exception raised.
"""
result = self.__super_popitem()
self._p_changed = 1
return result
# Old implementations (prior to 2001; see
# https://github.com/zopefoundation/ZODB/commit/c64281cf2830b569eed4f211630a8a61d22a0f0b#diff-b0f568e20f51129c10a096abad27c64a)
# used ``_container`` rather than ``data``. Use a descriptor to provide
# ``data`` when we have ``_container`` instead
@default
def data(self):
# We don't want to cause a write on read, so we're careful not to
# do anything that would cause us to become marked as changed, however,
# if we're modified, then the saved record will have data, not
# _container.
data = self.__dict__.pop('_container')
self.__dict__['data'] = data
return data