On Nov 18, 8:45 pm, Phlip <phlip2...@gmail.com> wrote:
> Pythonistas:
>
> If everyone likes this post, then the code is a "snippet" for
> community edification. Otherwise, it's a question: How to do this kind
> of thing better?
>
> I want a dict() variant that passes these test cases:
>
> map = Map()
> assert not(map.has_key('_default'))
>
> map = Map(yo='dude')
> assert map['yo'] == 'dude'
> assert map.yo == 'dude'
> assert None == map['whatever']
> assert not(map.has_key('_default'))
>
> map = Map(yo='dude', _default='q')
> assert 'q' == map['whatever']
> assert not(map.has_key('_default'))
>
> That's like Bunch, but with a default value. (That makes code with
> excess if statements less likely.)
>
> So here's the implementation:
>
> def Map(*args, **kwargs):
> value = kwargs.get('_default', None)
> if kwargs.has_key('_default'): del kwargs['_default']
>
> class _DefMap(dict):
> def __init__(self, *a, **kw):
> dict.__init__(self, *a, **kw)
> self.__dict__ = self
>
> def __getitem__(self, key):
> if not self.has_key(key): self[key] = value
> return dict.__getitem__(self, key)
>
> return _DefMap(*args, **kwargs)
>
> --
> Phlip
> http://bit.ly/ZeekLand
Looks like some combination of defaultdict and namedtuple.
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