D'Arcy J.M. Cain <da...@druid.net> wrote:
> On Fri, 19 Jun 2009 13:17:24 -0500
> Amita Ekbote <amita.ekb...@gmail.com> wrote:
> > I am retrieving values from a database in the form of a dictionary so
> > I can access the values as d['column'] and I was wondering if there is
> > a way to convert the hash to a struct like format so i can just say
> > d.column. Makes it easier to read and understand.
>
> Are there enough clues here?
>
> class MyDict(dict):
> def __getattribute__(self, name):
> return dict.__getattribute__(self, name)
>
> def __getattr__(self, name):
> return self.get(name, 42)
>
> x = MyDict({'a': 1, 'b': 2, 'values': 3})
That is my preferred solution - subclass dict rather than make a new
type... I use this a lot for returning results from databases.
Here is a more fleshed out version. Changing KeyError to
AttributeError is necessary if you want the object to pickle.
class MyDict(dict):
"""
A dictionary with attribute access also.
If a builtin dictionary method collides with a member of the
dictionary, the member function will win.
"""
def __getattr__(self, name):
try:
return super(db_dict, self).__getitem__(name)
except KeyError:
raise AttributeError("%r object has no attribute %r" %
(self.__class__.__name__, name))
def __setattr__(self, name, value):
return super(db_dict, self).__setitem__(name, value)
def __delattr__(self, name):
try:
return super(db_dict, self).__delitem__(name)
except KeyError:
raise AttributeError("%r object has no attribute %r" %
(self.__class__.__name__, name))
def copy(self):
return MyDict(self)
> print x.a
> print x.z
> print x.values
>
> Big question - what should the last line display? If you expect "3"
> and not "<built-in method values of MyDict object at 0xbb82838c>" then
> you need to reconsider the above implementation. Thinking about the
> question may change your opinion about this being a good idea after
> all.
Indeed!
--
Nick Craig-Wood <n...@craig-wood.com> -- http://www.craig-wood.com/nick
--
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