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
|
class classinstancemethod(object):
"""
Acts like a class method when called from a class, like an
instance method when called by an instance. The method should
take two arguments, 'self' and 'cls'; one of these will be None
depending on how the method was called.
"""
def __init__(self, func):
self.func = func
def __get__(self, obj, type=None):
return _methodwrapper(self.func, obj=obj, type=type)
class _methodwrapper(object):
def __init__(self, func, obj, type):
self.func = func
self.obj = obj
self.type = type
def __call__(self, *args, **kw):
assert not kw.has_key('self') and not kw.has_key('cls'), (
"You cannot use 'self' or 'cls' arguments to a "
"classinstancemethod")
return self.func(*((self.obj, self.type) + args), **kw)
def __repr__(self):
if self.obj is None:
return ('<bound class method %s.%s>'
% (self.type.__name__, self.func.func_name))
else:
return ('<bound method %s.%s of %r>'
% (self.type.__name__, self.func.func_name, self.obj))
class ClassInitMeta(type):
def __new__(meta, class_name, bases, new_attrs):
cls = type.__new__(meta, class_name, bases, new_attrs)
if (new_attrs.has_key('__classinit__')
and not isinstance(cls.__classinit__, staticmethod)):
setattr(cls, '__classinit__',
staticmethod(cls.__classinit__.im_func))
if hasattr(cls, '__classinit__'):
cls.__classinit__(cls, new_attrs)
return cls
def build_properties(cls, new_attrs):
"""
Given a class and a new set of attributes (as passed in by
__classinit__), create or modify properties based on functions
with special names ending in __get, __set, and __del.
"""
for name, value in new_attrs.items():
if (name.endswith('__get') or name.endswith('__set')
or name.endswith('__del')):
base = name[:-5]
if hasattr(cls, base):
old_prop = getattr(cls, base)
if not isinstance(old_prop, property):
raise ValueError(
"Attribute %s is a %s, not a property; function %s is named like a property"
% (base, type(old_prop), name))
attrs = {'fget': old_prop.fget,
'fset': old_prop.fset,
'fdel': old_prop.fdel,
'doc': old_prop.__doc__}
else:
attrs = {}
attrs['f' + name[-3:]] = value
if name.endswith('__get') and value.__doc__:
attrs['doc'] = value.__doc__
new_prop = property(**attrs)
setattr(cls, base, new_prop)
|
