Jason wrote:
> Here's my general-purpose solution for doing this:
>
> class Dict2Class(object):
> """
> Update like a dictionary, but expose the keys as class properties.
I'm afraid that's wrong. It's wrong twice:
* Properties are computed attributes. These are not, they are regular
attributes.
* Class attributes are shared between all instances. These are not, so they
are instance attributes (or just regular "attributes" without
qualification), not class attributes.
> def __init__(self, *e, **f):
> self.__dict__ = dict(*e, **f)
You're updating the instance __dict__, not the class __dict__. Hence they
are instance attributes.
This is the correct thing to do, but if you wanted to share keys and values
between all instances, you would use class attributes:
def __init__(self, *e, **f):
self.__class__.__dict__ = dict(*e, **f)
As far as properties, in this case there's no sensible reason for making
them properties. (Properties have their uses, but this isn't one of them.)
However, since I'm not sensible *grin*, here's a quick-and-dirty version
that works, for some definition of "works":
class Dict2PropertyClass(object):
# Like Dict2Class except using properties.
def __init__(self, *e, **f):
for key, value in dict(*e, **f).items():
private = '_' + key
setattr(self, private, value)
getter = lambda self, private=private: getattr(self, private)
setter = (
lambda self, value, private=private:
setattr(self, private, value)
)
setattr(self.__class__, key,
property(getter, setter)
)
Getting update() working with this version is left as an exercise for the
masochistic *wink*
--
Steven
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