Coverage for python/lsst/daf/persistence/readProxy.py : 69%

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1#!/usr/bin/env python
3#
4# LSST Data Management System
5# Copyright 2008, 2009, 2010 LSST Corporation.
6#
7# This product includes software developed by the
8# LSST Project (http://www.lsst.org/).
9#
10# This program is free software: you can redistribute it and/or modify
11# it under the terms of the GNU General Public License as published by
12# the Free Software Foundation, either version 3 of the License, or
13# (at your option) any later version.
14#
15# This program is distributed in the hope that it will be useful,
16# but WITHOUT ANY WARRANTY; without even the implied warranty of
17# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18# GNU General Public License for more details.
19#
20# You should have received a copy of the LSST License Statement and
21# the GNU General Public License along with this program. If not,
22# see <http://www.lsstcorp.org/LegalNotices/>.
23#
25# -*- python -*-
27"""This module defines the ReadProxy class."""
29from .persistence import ReadProxyBase
32class ReadProxy(ReadProxyBase):
33 """ReadProxy provides a lazy-loading object that is initialized by a
34 callback function set in ReadProxy's constructor. Adapted from
35 peak.util.proxies.LazyProxy, which was written by Phillip J. Eby
36 (peak@eby-sarna.com)."""
38 __slots__ = ('__cache__', '__callback__')
40 def __init__(self, func):
41 set_callback(self, func)
43 def __getattr__(self, attr):
44 getattr(self.__subject__, attr)
46 def __setattr__(self, attr, val):
47 setattr(self.__subject__, attr, val)
49 def __delattr__(self, attr):
50 delattr(self.__subject__, attr)
52 def __bool__(self):
53 return bool(self.__subject__)
55 def __getitem__(self, arg):
56 return self.__subject__[arg]
58 def __setitem__(self, arg, val):
59 self.__subject__[arg] = val
61 def __delitem__(self, arg):
62 del self.__subject__[arg]
64 def __getslice__(self, i, j):
65 return self.__subject__[i:j]
67 def __setslice__(self, i, j, val):
68 self.__subject__[i:j] = val
70 def __delslice__(self, i, j):
71 del self.__subject__[i:j]
73 def __contains__(self, ob):
74 return ob in self.__subject__
76 for name in 'repr str hash len abs complex int long float iter oct hex'.split():
77 exec("def __%s__(self): return %s(self.__subject__)" % (name, name))
79 for name in 'cmp', 'coerce', 'divmod':
80 exec("def __%s__(self, ob): return %s(self.__subject__, ob)" % (name,
81 name))
83 for name, op in [
84 ('lt', '<'), ('gt', '>'), ('le', '<='), ('ge', '>='),
85 ('eq', '=='), ('ne', '!=')
86 ]:
87 exec("def __%s__(self, ob): return self.__subject__ %s ob" % (name, op))
89 for name, op in [('neg', '-'), ('pos', '+'), ('invert', '~')]:
90 exec("def __%s__(self): return %s self.__subject__" % (name, op))
92 for name, op in [
93 ('or', '|'), ('and', '&'), ('xor', '^'),
94 ('lshift', '<<'), ('rshift', '>>'),
95 ('add', '+'), ('sub', '-'), ('mul', '*'), ('div', '/'),
96 ('mod', '%'), ('truediv', '/'), ('floordiv', '//')
97 ]:
98 exec((
99 "def __%(name)s__(self,ob):\n"
100 " return self.__subject__ %(op)s ob\n"
101 "\n"
102 "def __r%(name)s__(self,ob):\n"
103 " return ob %(op)s self.__subject__\n"
104 "\n"
105 "def __i%(name)s__(self,ob):\n"
106 " self.__subject__ %(op)s=ob\n"
107 " return self\n"
108 ) % locals())
110 del name, op
112 # Oddball signatures
114 def __rdivmod__(self, ob):
115 return divmod(ob, self.__subject__)
117 def __pow__(self, *args):
118 return pow(self.__subject__, *args)
120 def __ipow__(self, ob):
121 self.__subject__ **= ob
122 return self
124 def __rpow__(self, ob):
125 return pow(ob, self.__subject__)
128get_callback = ReadProxy.__callback__.__get__
129set_callback = ReadProxy.__callback__.__set__
130get_cache = ReadProxy.__cache__.__get__
131set_cache = ReadProxy.__cache__.__set__
134def _subject(self, get_cache=get_cache, set_cache=set_cache):
135 try:
136 return get_cache(self)
137 except AttributeError:
138 set_cache(self, get_callback(self)())
139 return get_cache(self)
142ReadProxy.__subject__ = property(_subject, set_cache)
143del _subject