how to scrutch a dict()

[Ethan Furman]

John Nagle wrote:
> On 10/20/2010 9:32 PM, Phlip wrote:
> 
>> Not Hyp:
>>
>> def _scrunch(**dict):
>>      result = {}
>>
>>      for key, value in dict.items():
>>          if value is not None:  result[key] = value
>>
>>      return result
>>
>> That says "throw away every item in a dict if the Value is None".
>>
>> Are there any tighter or smarmier ways to do that?
> 
> 
> Yes.
> 
> class nonnulldict(dict) :
>     def __setitem__(self, k, v) :
>         if not (v is None) :
>            dict.__setitem__(self, k, v)
> 
> That creates a subclass of "dict" which ignores stores of None values.
> So you never store the unwanted items at all.

It's going to take more work than that...

--> nnd = nonnulldict(spam='eggs', ham=None, parrot=1)
--> nnd
{'ham': None, 'parrot': 1, 'spam': 'eggs'}
--> d['more_hame'] = None
--> nnd.update(d)
--> nnd
{10000:True, 'more_hame':None, 'ham':None, 'parrot':1, 'spam':'eggs'}

Tested in both 2.5 and 3.1.

~Ethan~