*** empty log message ***

src/ZODB/Persistence.py

+#!/usr/local/bin/python 
+# $What$
+
+__doc__='''Python implementation of persistent base types
+
+
+$Id: Persistence.py,v 1.1 1997/02/11 13:14:06 jim Exp $'''
+#     Copyright 
+#
+#       Copyright 1996 Digital Creations, L.C., 910 Princess Anne
+#       Street, Suite 300, Fredericksburg, Virginia 22401 U.S.A. All
+#       rights reserved.  Copyright in this software is owned by DCLC,
+#       unless otherwise indicated. Permission to use, copy and
+#       distribute this software is hereby granted, provided that the
+#       above copyright notice appear in all copies and that both that
+#       copyright notice and this permission notice appear. Note that
+#       any product, process or technology described in this software
+#       may be the subject of other Intellectual Property rights
+#       reserved by Digital Creations, L.C. and are not licensed
+#       hereunder.
+#
+#     Trademarks 
+#
+#       Digital Creations & DCLC, are trademarks of Digital Creations, L.C..
+#       All other trademarks are owned by their respective companies. 
+#
+#     No Warranty 
+#
+#       The software is provided "as is" without warranty of any kind,
+#       either express or implied, including, but not limited to, the
+#       implied warranties of merchantability, fitness for a particular
+#       purpose, or non-infringement. This software could include
+#       technical inaccuracies or typographical errors. Changes are
+#       periodically made to the software; these changes will be
+#       incorporated in new editions of the software. DCLC may make
+#       improvements and/or changes in this software at any time
+#       without notice.
+#
+#     Limitation Of Liability 
+#
+#       In no event will DCLC be liable for direct, indirect, special,
+#       incidental, economic, cover, or consequential damages arising
+#       out of the use of or inability to use this software even if
+#       advised of the possibility of such damages. Some states do not
+#       allow the exclusion or limitation of implied warranties or
+#       limitation of liability for incidental or consequential
+#       damages, so the above limitation or exclusion may not apply to
+#       you.
+#  
+#
+# 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
+#
+# $Log: Persistence.py,v $
+# Revision 1.1  1997/02/11 13:14:06  jim
+# *** empty log message ***
+#
+#
+# 
+__version__='$Revision: 1.1 $'[11:-2]
+
+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.
+
+    Data are not saved automatically.  To save an object's state, call
+    the object's '__save__' method.
+
+    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_' in the state.
+
+    """ 
+    _p_oid=None	       # A Persistent object-id, unique within a jar
+    _p_changed=None    # A flag indicating whether the object has changed
+    _p_read_time=0     # The time when the object was read.
+    _p_jar=None        # The last jar that this object was stored in.
+    
+    def __getattr__(self,key):
+	' '
+	try: setstate=self.__dict__['_p_setstate']
+	except: raise AttributeError, key
+	setstate(self)
+	try: return self.__dict__[key]
+	except: raise AttributeError, key
+
+    def _p___init__(self,oid,jar):
+	d=self.__dict__
+	if self._p_oid is None:
+	    d['_p_oid']=oid
+	if self._p_oid==oid:
+	    newstate={}
+	    for key in d.keys():
+		if key[:3] != '_p_':
+		    newstate[key]=d[key]
+		    del d[key]		
+	    d['_p_newstate']=newstate
+	    d['_p_jar']=jar
+	    d['_p_setstate']=jar.setstate
+	    d['_p_changed']=0
+
+    def _p___reinit__(self,oid,jar,copy):
+	d=self.__dict__
+	cd=copy.__dict__
+	if self._p_oid is None: d['_p_oid']=oid
+	if self._p_oid==oid:
+	    newstate={}
+	    for key in cd.keys():
+		if key[:3] != '_p_': newstate[key]=cd[key]
+	    for key in d.keys():
+		if key[:3] != '_p_': del d[key]
+	    d['_p_newstate']=newstate
+	    d['_p_jar']=jar
+	    d['_p_setstate']=jar.setstate
+	    d['_p_changed']=0
+
+    def __setattr__(self,key,value):
+	' '
+	if key[:3]=='_p_':
+	    self.__dict__[key]=value
+	    return
+    
+	try:
+	    setstate=self.__dict__['_p_setstate']
+	    try: setstate(self)
+	    except: raise TypeError, (sys.exc_type, sys.exc_value,
+				      sys.exc_traceback)
+	except KeyError: pass
+	except TypeError, v: raise v[0], v[1], v[2]
+
+	self.__dict__[key]=value
+	self.__changed__(1)
+
+    def __repr__(self):
+	' '
+	return '<%s instance at %s>' % (self.__class__.__name__,hex(id(self)))
+    
+    def __getstate__(self):
+	
+	# First, update my state, if necessary:
+	try:
+	    setstate=self.__dict__['_p_setstate']
+	    try: setstate(self)
+	    except: raise TypeError, (sys.exc_type, sys.exc_value,
+				      sys.exc_traceback)
+	except KeyError: pass
+	except TypeError, v: raise v[0], v[1], v[2]
+
+	state={}
+	d=self.__dict__
+	for k in d.keys():
+	    if k[:3] != '_p_':
+		state[k]=d[k]
+	return state
+
+    def __setstate__(self,state):
+	d=self.__dict__
+	for k in state.keys():
+	    d[k]=state[k]
+	return state
+
+    def __save__(self):
+	'''\
+	Update the object in a persistent database.
+	'''
+	jar=self._p_jar
+	if jar: jar.store(self)
+
+    __del__=__save__
+
+    def __changed__(self,value=None):
+	'''\
+	Flag or determine whether an object has changed
+	
+	If a value is specified, then it should indicate whether an
+	object has or has not been changed.  If no value is specified,
+	then the return value will indicate whether the object has
+	changed.
+	'''	
+	if value is not None:
+	    self.__dict__['_p_changed']=value
+	else:
+	    return self._p_changed
+
+try: from cPersistence import Persistent
+except: pass
+	
+class PersistentMapping(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.
+    """
+
+    def __init__(self,container=None):
+	if container is None: container={}
+	self._container=container
+
+    def __getitem__(self, key):
+	return self._container[key]
+
+    def __setitem__(self, key, v):
+	self._container[key]=v
+	try: del self._keys
+	except: pass
+	self.__changed__(1)
+
+    def __delitem__(self, key):
+	del self._container[key]
+	try: del self._keys
+	except: pass
+	self.__changed__(1)
+
+    def __len__(self):     return len(self._container)
+
+    def keys(self):
+	try: return self._keys
+	except: pass
+	keys=self._keys=filter(
+	    lambda k: k[:1]!='_',
+	    self._container.keys())
+	keys.sort()
+	return keys
+
+    def values(self):
+	return map(lambda k, d=self: d[k], self.keys())
+
+    def items(self):
+	return map(lambda k, d=self: (k,d[k]), self.keys())
+
+    def has_key(self,key): return self._container.has_key(key)
+