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
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
import NewBuiltins
class AcquisitionMixin:
""" Mixin class allowing implicit acquisition of attributes from
objects up a containment hierachy.
To enable this feature, an object 'b' contained in another
object 'a' must set the instance variable b.baseobj to
a. The search is done recursively until either an exception
is raised by the queried object or the object is found.
Attributes that strt with an underscore ('_') can not
be acquired. Be careful when acquiring methods: the method
will be executed in the baseobjects context, not the one
it is acquired into.
See the documentation of acquire() for details.
"""
baseobj = None # Base object ("containing" this object)
# Implicit acquisition
__getattr__ = acquire # Use the (new) builtin acquire() to implement
# the acquisition mechanism
def __init__(self,*args,**kw):
""" Create the object and call startup(*args,**kw)
- if you give a keyword 'baseobj' then its parameter
is used to set the baseobj for acquisition; the keyword
is then deleted from kw
"""
# Set baseobj for acquisition to work properly
baseobj = kw.get('baseobj',None)
if baseobj is not None:
self.baseobj = baseobj
del kw['baseobj']
# call startup()
apply(self.startup,args,kw)
def startup(self,*args,**kw):
""" Override this to init the instance.
"""
pass
class PythonAcquisitionMixin(AcquisitionMixin):
def __getattr__(self,name,
getattr=getattr,AttributeError=AttributeError):
if name[0] != '_':
return getattr(self.baseobj,name)
raise AttributeError,name
# Localize these here for speed
baseobj = AcquisitionMixin.baseobj
__init__ = AcquisitionMixin.__init__
startup = AcquisitionMixin.startup
def _test():
class C(AcquisitionMixin):
a = 2
x = 9
class D(AcquisitionMixin):
b = 3
class E(AcquisitionMixin):
c = 4
# Setup acquisition chain
c = C()
d = D(baseobj=c)
e = E(baseobj=d)
# Give implicit acquisition a go...
print c.a, d.a, e.a
print d.b, e.b
print e.c
d.a = 5
print c.a, d.a, e.a
c.b = 1
print c.b, d.b, e.b
print
# Performance comparism:
print 'Performance:'
print
import time
l = range(100000)
class C(AcquisitionMixin):
x = 9
class D(AcquisitionMixin):
y = 8
class E(AcquisitionMixin):
z = 7
# Setup acquisition chain
c = C()
d = D(baseobj=c)
e = E(baseobj=d)
t = time.time()
for i in l:
e.x
e.y
e.z
print 'AcquisitionMixin:',time.time() - t,'seconds'
class C(PythonAcquisitionMixin):
x = 9
class D(PythonAcquisitionMixin):
y = 8
class E(PythonAcquisitionMixin):
z = 7
# Setup acquisition chain
c = C()
d = D(baseobj=c)
e = E(baseobj=d)
t = time.time()
for i in l:
e.x
e.y
e.z
print 'PythonAcquisitionMixin:',time.time() - t,'seconds'
if __name__ == '__main__':
_test()
|
