Using inner dict as class interface

Dave Angel d at davea.name
Wed Jan 16 16:05:26 CET 2013


On 01/16/2013 09:42 AM, Florian Lindner wrote:
> Hello,
>
> I have a:
>
> class C:
>     def __init__(self):
>        d = dict_like_object_created_somewhere_else()
>
>    def some_other_methods(self):
>      pass
>
>
> class C should behave like a it was the dict d. So I could do:

Is it a specific requirement that the class NOT be derived from dict?  
Are you trying to look like a dict, but with a few extra features?  Or 
must you have a dict somewhere else (singleton ??!) that you're trying 
to tie this to as a proxy.

Assuming you really have to tie this to some other dict, the first thing 
you need to do is save d, perhaps as a line like:

     self.d = dict_like_ob....

>
> c = C()
> print c["key"]
> print len(c)
>
> but also
>
> c.some_other_method()
>
> How can I achieve that? Do I need to define all methods like
> __getitem__, __len__, ... (what else?)

See http://docs.python.org/reference/datamodel.html#special-method-names

Because you're duck-typing, you don't need them all, just the ones your 
user will need.

> to access the inner dict or is
> there something more slick?
>

The more slick is to derive from dict.

--
DaveA




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