Peter, thanks for your response.
Sure, you are right when you say that's easier to use standard attribute
assigning via __init__.
But my intention was:
- reducing the complexiticity of __init__
- avoiding boiler-plates (mostly property descriptors inside of the main class)
- creating instances (for complex data strings) only if they will be needed,
otherwise use default instances (descriptors)
- make it prossible that the data structure can be used in static context -
like MyClass.attr - to get default values
Standard procedure:
>>>class C:
>>> def __init__(self, one, two=None, three=None, four=None, five=None, ...):
>>> if not two is None:
>>> self.two = Value(two)
>>> else:
>>> self.two = Value(self.DEFAULT_4_TWO)
>>> ...
vs:
>>>class C:
>>>
>>> two = MyDescriptor('default for two')
>>>
>>> def __init__(self, one, two=None, three=None, four=None, five=None, ...):
>>> self.one = one
>>> if not two is None:
>>> self.two = two
>>> ...
Probably it will be necessary to set the attribute at first access.
Alternatively it may be possible to observe the descriptor til an attribute
will be setted e.g. instance.attr.value = 'whatever'. At this point a new
instance (like Value) should be created on obj.__dict__.
It's the procedure what I'm looking for. ;)
Kind Regards,
Chris
--
http://mail.python.org/mailman/listinfo/python-list
