1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
# Copyright 2007 World Wide Workshop Foundation
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#
# If you find this activity useful or end up using parts of it in one of your
# own creations we would love to hear from you at info@WorldWideWorkshop.org !
#
import sys
class Persistent(type):
'''Metaclass providing object persistence'''
def __init__(cls, name, bases, dct):
super(Persistent, cls).__init__(name, bases, dct)
setattr(cls, '__dirty__', False)
setattr(cls, '__properties__', filter(_is_persistent, dct.iteritems()))
from util.journalpickler import dumps, loads
setattr(cls, 'dumps', dumps)
setattr(cls, 'loads', loads)
def PersistentProperty(function):
'''Decorator to set up persistent properties
Adapted from: http://wiki.python.org/moin/PythonDecoratorLibrary
'''
func_locals = {'doc':function.__doc__}
def fgetter(obj, name, getter, fdef):
attr_name = '_' + obj.__class__.__name__ + '__' + name
if not hasattr(obj, attr_name):
setattr(obj, attr_name, fdef(obj))
return getter(obj)
def fsetter(obj, name, setter, value):
setattr(obj, '__dirty__', True) # TODO -> Propogate dirty flag up to any
# parent objects ?
return setter(obj, value)
def introspect(frame, event, arg):
if event == 'return':
locals = frame.f_locals
if locals.has_key('delete'):
func_locals['fdel'] = locals['delete']
if locals.has_key('set'):
func_locals['fset'] = \
lambda obj, value : fsetter(obj, function.__name__, locals['set'], value)
if locals.has_key('default'):
get_function = lambda obj : fgetter(obj, function.__name__, locals['get'], locals['default'])
else:
get_function = lambda obj : fgetter(obj, function.__name__, locals['get'], lambda x : None)
get_function.__decorator__ = PersistentProperty # tag the getter so we can id the
# decorator. Yeah, it's ugly.
func_locals['fget'] = get_function
sys.settrace(None)
return introspect
sys.settrace(introspect)
function()
return property(**func_locals)
# a wee bit ugly
def _is_persistent(item):
'''check if property is decorated with PersistentProperty decorator'''
prop = item[1]
return type(prop) is property and \
hasattr(prop.fget, '__decorator__') and \
prop.fget.__decorator__ is PersistentProperty
|
