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ConfigurableMeta.py
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1 # File: AthenaCommon/python/ConfigurableMeta.py
2 # Author: Wim Lavrijsen (WLavrijsen@lbl.gov)
3
4 import GaudiKernel.PropertyProxy as PropertyProxy
5
6
7 # data
8 __version__ = '1.0.1'
9 __author__ = 'Wim Lavrijsen (WLavrijsen@lbl.gov)'
10
11 __all__ = ['ConfigurableMeta']
12
13 # this metaclass installs PropertyProxy descriptors for Gaudi properties
14
15
16 class ConfigurableMeta(type):
17 """The setting of Gaudi component properties needs to be deferred and
18 history of who set what where needs to be collected. This is done
19 by using PropertyProxy descriptors rather than the default ones."""
20
21 def __new__(self, name, bases, dct):
22 # enfore use of classmethod for getType() and setDefaults()
23 if 'getType' in dct and not isinstance(dct['getType'], classmethod):
24 dct['getType'] = classmethod(dct['getType'])
25
26 if 'setDefaults' in dct and not isinstance(dct['setDefaults'], classmethod):
27 dct['setDefaults'] = classmethod(dct['setDefaults'])
28
29 # collect what are properties (basically, any public name; C++ variables
30 # shouldn't start with an '_' because of portability constraints, hence
31 # it is safe to assume that any such vars are python private ones)
32 newclass = type.__new__(self, name, bases, dct)
33
34 # cache references of instances by name for duplicate removal
35 newclass.configurables = {}
36
37 # loop over slots, which are all assumed to be properties, create proxies, defaults
38 properties = {}
39 slots = dct.get('__slots__')
40 if slots:
41 props = [x for x in slots if x[0] != '_']
42 propDict = dct.get('_propertyDocDct')
43 for prop in props:
44 docString = propDict and propDict.get(prop)
45 if type(slots) == dict:
46 default = slots[prop]
47 else:
48 default = None
49 proxy = PropertyProxy.PropertyProxyFactory(
50 getattr(newclass, prop), docString, default)
51
52 properties[prop] = proxy
53 setattr(newclass, prop, proxy)
54
55 # complete set of properties includes those from base classes
56 for base in bases:
57 try:
58 bprops = base._properties.copy()
59 bprops.update(properties)
60 properties = bprops
61 except AttributeError:
62 pass
63
64 newclass._properties = properties
65
66 return newclass
67
68 def __call__(cls, *args, **kwargs):
69 """To Gaudi, any object with the same type/name is the same object. Hence,
70 this is mimicked in the configuration: instantiating a new Configurable
71 of a type with the same name will return the same instance."""
72
73 # Get the instance: `singleton' logic needs to be in __new__, not here,
74 # for compatibililty with pickling.)
75 cfg = cls.__new__(cls, *args, **kwargs)
76
77 # Initialize the object, if not done already.
78 if not hasattr(cfg, '_initok') or not cfg._initok:
79 cls.__init__(cfg, *args, **kwargs)
80
81 return cfg
GaudiKernel.PropertyProxy
Definition: PropertyProxy.py:1
gaudirun.type
type
Definition: gaudirun.py:133
GaudiKernel.ConfigurableMeta.ConfigurableMeta.__new__
def __new__(self, name, bases, dct)
Definition: ConfigurableMeta.py:21
GaudiKernel.ConfigurableMeta.ConfigurableMeta
Definition: ConfigurableMeta.py:16
GaudiKernel.ConfigurableMeta.ConfigurableMeta.__call__
def __call__(cls, args, kwargs)
Definition: ConfigurableMeta.py:68