<top_posting>
I like this version very much. I'm ready to put this into practice to see
how it
works in practice.
A minor point: I envision this to be used in a context where all key values
are
strings (legal attribute identifiers). But constructing an AttrClass from a
dict
or setting values directly with the dict syntax can allow any valid item as
a
dict key -- specifically numbers, tuples, etc. If the user of this class
chooses
to do this, a number of the items become inaccessible to the attribute
syntax.
In my case, I think this won't be a problem since I anticipate that values
will
always be set by the attribute syntax, but it might be an issue for other
uses.
</top_posting>
On Fri, Sep 4, 2009 at 6:01 AM, Jan Kaliszewski <z...@chopin.edu.pl> wrote:
> [originally from python-list@python.org,
> crossposted to python-id...@python.org]
>
[snip]
> class AttrDict(dict): # (or maybe from OrderedDict)
> "It's only a model. (Shhh!)"
>
> def __getattr__(self, name):
> if name.startswith('_'):
> raise AttributeError("AttrDict's key can't "
> "start with underscore")
> else:
> return self[name]
>
> def __setattr__(self, name, value):
> self[name] = value
>
> def __delattr__(self, name):
> del self[name]
>
> def __repr__(self):
> return '{0}({1})'.format(self.__class__.__name__,
> dict.__repr__(self))
> def __str__(self):
> return self._as_str()
>
> def _gen_format(self, indwidth, indstate):
> indst = indstate * ' '
> ind = (indstate + indwidth) * ' '
> yield ('\n' + indst + '{' if indstate else '{')
> for key, val in self.items():
> valstr = (str(val) if not isinstance(val, AttrDict)
> else val._as_str(indwidth, indstate + indwidth))
> yield '{ind}{key}: {valstr}'.format(ind=ind, key=key,
> valstr=valstr)
> yield indst + '}'
>
> def _as_str(self, indwidth=4, indstate=0):
> return '\n'.join(self._gen_format(indwidth, indstate))
>
> def _as_dict(self):
> return dict.copy(self)
>
>
> # Test code:
> if __name__ == '__main__':
> struct = AttrDict()
> struct.first = 1
> struct.second = 2.0
> struct.third = '3rd'
> struct.fourth = [4]
> print(struct)
> # output:
> # {
> # 'second': 2.0
> # 'fourth': [4]
> # 'third': '3rd'
> # 'first': 1
> # }
>
> del struct.fourth
>
> print(repr(struct))
> # output:
> # AttrDict({'second': 2.0, 'third': '3rd', 'first': 1})
>
> print(struct.first) # (static access)
> # output:
> # 1
>
> for x in ('first', 'second', 'third'):
> print(struct[x]) # (dynamic access)
> # output:
> # 1
> # 2.0
> # 3rd
>
> struct.sub = AttrDict(a=1, b=2, c=89)
> print(struct._as_dict())
> # output:
> # {'second': 2.0, 'sub': AttrDict({'a': 1, 'c': 89, 'b': 2}),\
> # 'third': '3rd', 'first': 1}
>
> print(struct._as_str(8))
> # output:
> # {
> # second: 2.0
> # sub:
> # {
> # a: 1
> # c: 89
> # b: 2
> # }
> # third: 3rd
> # first: 1
> # }
>
>
> What do you think about it?
>
> Cheers,
> *j
>
> --
> Jan Kaliszewski (zuo) <z...@chopin.edu.pl>
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>
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