[Python-Dev] Add a "transformdict" to collections

[Hrvoje Niksic]

On 09/10/2013 02:24 PM, Paul Moore wrote:
>>>> td['FOO'] = 42
>>>> td['foo'] = 32
>>>> list(td.keys())
>
> ['FOO'] or ['foo']? Both answers are justifiable.

Note that the same question can be reasonably asked for dict itself:

 >>> d = {}
 >>> d[1.0] = 'foo'
 >>> d[1] = 'bar'
 >>> d
{1.0: 'bar'}

So, dict.__setitem__ only replaces the value, leaving the original key 
in place. transformdict should probably do the same, returning 'FOO' in 
your example.