Dictionary .keys() and .values() should return a set [withPython3000 in mind]

[Delaney, Timothy (Tim)]

Paul Rubin wrote:

> "cmdrrickhunter at yaho.com" <conrad.ammon at gmail.com> writes:
>> And a "view" of the dictionary is orders faster than creating a copy
>> of it (which is required to keep k0 from changing in your example). 
>> If you're LUCKY, copying a dictionary is O(n),
> 
> There are ways to do it so you don't have to copy, but the dict would
> then no longer be a straightforward hash table.

Plus copy-on-write isn't something you want in general - it's *much*
slower since it needs to copy the internal data every time it's
modified. The vast majority of uses of data structures does not involve
concurrent modification.

Tim Delaney