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##############################################################################
#
# Copyright (c) 1996-1998, Digital Creations, Fredericksburg, VA, USA.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# o Redistributions of source code must retain the above copyright
# notice, this list of conditions, and the disclaimer that follows.
#
# o Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions, and the following disclaimer in
# the documentation and/or other materials provided with the
# distribution.
#
# o Neither the name of Digital Creations nor the names of its
# contributors may be used to endorse or promote products derived
# from this software without specific prior written permission.
#
#
# THIS SOFTWARE IS PROVIDED BY DIGITAL CREATIONS AND CONTRIBUTORS *AS IS*
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL DIGITAL
# CREATIONS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
# TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
# DAMAGE.
#
#
# If you have questions regarding this software, contact:
#
# Digital Creations, L.C.
# 910 Princess Ann Street
# Fredericksburge, Virginia 22401
#
# info@digicool.com
#
# (540) 371-6909
#
##############################################################################
__doc__='''Python implementation of a persistent base types
$Id: Persistence.py,v 1.16 1998/10/23 21:40:15 jim Exp $'''
__version__='$Revision: 1.16 $'[11:-2]
try:
from cPersistence import Persistent
except:
class Persistent:
"""\
Persistent object support mix-in class
When a persistent object is loaded from a database, the object's
data is not immediately loaded. Loading of the objects data is
defered until an attempt is made to access an attribute of the
object.
The object also tries to keep track of whether it has changed. It
is easy for this to be done incorrectly. For this reason, methods
of subclasses that change state other than by setting attributes
should: 'self.__changed__(1)' to flag instances as changed.
You must not override the object's '__getattr__' and '__setattr__'
methods. If you override the objects '__getstate__' method, then
you must be careful not to include any attributes with names
starting with '_p_' or '_v_' in the state.
"""
_p_oid=None # A Persistent object-id, unique within a jar
_p_changed=0 # The object state: None=ghost, 0=normal, 1=changed
_p_jar=None # The last jar that this object was stored in.
def _p___init__(self,oid,jar):
"""Post creation initialization
This is *only* used if we have __getinitargs__!
"""
d=self.__dict__
if d:
newstate={}
for key in d.keys():
if key[:3] != '_p_':
newstate[key]=d[key]
del d[key]
if newstate: d['_p_newstate']=newstate
d['_p_oid']=oid
d['_p_jar']=jar
d['_p_changed']=None
def _p_deactivate(self,copy=None):
if copy is None: newstate=None
else: newstate=copy.__dict__
d=self.__dict__
oid=self._p_oid
jar=self._p_jar
d.clear()
if newstate: d['_p_newstate']=newstate
d['_p_oid']=oid
d['_p_jar']=jar
d['_p_changed']=None
_p___reinit=_p_deactivate # Back. Comp.
def __getattr__(self,key):
'Get an item'
if self._p_changed is None and key[:3] != '_p_':
self._p_jar.setstate(self)
if self.__dict__.has_key(key): return self.__dict__[key]
raise AttributeError, key
def __setattr__(self,key,value):
' '
changed=self._p_changed
if changed:
self.__dict__[key]=value
return
k=key[:3]
if k=='_p_' or k=='_v_':
self.__dict__[key]=value
return
jar=self._p_jar
if jar is None:
self.__dict__[key]=value
return
d=self.__dict__
if changed is None:
d['_p_changed']=1
jar.setstate(self)
d[key]=value
try:
get_transaction().register(self)
d['_p_changed']=1
except: pass
def __changed__(self,v=-1):
old=self._p_changed
if v != -1:
if v and not old and self._p_jar is not None:
try: get_transaction().register(self)
except: pass
self._p_changed = not not v
return old
def __getstate__(self):
# First, update my state, if necessary:
if self._p_changed is None: self._p_jar.setstate(self)
state={}
d=self.__dict__
for k,v in d.items():
if k[:3] != '_p_' and k[:3] != '_v_': state[k]=v
return state
def __setstate__(self,state):
d=self.__dict__
for k,v in state.items(): d[k]=v
return state
def __save__(self):
'''\
Update the object in a persistent database.
'''
jar=self._p_jar
if jar and self._p_changed: jar.store(self)
def __repr__(self):
' '
return '<%s instance at %s>' % (self.__class__.__name__,
hex(id(self)))
def __inform_commit__(self,T,start_time):
jar=self._p_jar
if jar and self._p_changed: jar.store(self,T)
def __inform_abort__(self,T,start_time):
try: self._p_jar.abort(self,start_time)
except: pass
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