[Python-Dev] Add a "transformdict" to collections
lukas.lueg at gmail.com
Tue Sep 10 22:36:18 CEST 2013
Should'nt the key'ing behaviour be controlled by the type of the key
instead of the type of the container?
2013/9/10 MRAB <python at mrabarnett.plus.com>
> On 10/09/2013 20:08, Paul Moore wrote:
>> On 10 September 2013 19:31, Antoine Pitrou <solipsis at pitrou.net> wrote:
>>> I think it would be a flaw to have this detail implementation-defined.
>>>> This would be like saying that it is implementation-defined which
>>>> of A,B,C is returned from "A and B and C" if all are true.
>>> Ok, it seems everyone (except me :-)) agrees that it should return the
>>> first key value, so that's how it will be.
>> If you retain the first key value, it's easy enough for the
>> application to implement "retain the last" semantics:
>> del d[k]
>> d[k] = v
>> That would raise a KeyError is the key was missing. A better way is:
> d.pop(k, None)
> d[k] = v
> If you provide "retain the last", I can't see any obvious way of
>> implementing "retain the first" in application code without in effect
>> reimplementing the class.
>> "Retain the first" does feel more natural to me.
> Python-Dev mailing list
> Python-Dev at python.org
> Unsubscribe: https://mail.python.org/**mailman/options/python-dev/**
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Python-Dev