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

[MRAB]

On 10/09/2013 22:46, Antoine Pitrou wrote:
> On Tue, 10 Sep 2013 18:44:20 -0300
> "Joao S. O. Bueno" <jsbueno at python.org.br> wrote:
>> On 10 September 2013 18:06, Antoine Pitrou <solipsis at pitrou.net> wrote:
>> > On Tue, 10 Sep 2013 17:38:26 -0300
>> > "Joao S. O. Bueno" <jsbueno at python.org.br> wrote:
>> >> On 10 September 2013 16:08, Paul Moore <p.f.moore at gmail.com> wrote:
>> >> > 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.
>> >>
>> >> Which reminds one - this class should obviously have a method for
>> >> retrivieng the original key value, given a matching key -
>> >>
>> >> d.canonical('foo') -> 'Foo'
>> >
>> > I don't know. Is there any use case?
>> > (sure, it is trivially implemented)
>>
>> Well, I'd expect it to simply be there. I had not thought of
>> other usecases for the transformdict itself -
>
I had the same thought.

> Well, it is not here for dict, set, etc.
>
In those cases the key in the dict == the key you're looking for.

>> For example, in latim languages it is common to want
>> accented letters to match their unaccented counterparts
>> - pick my own first name "João" - if I'd use a transform to strip
>> the diactriticals, and have an user input "joao" - it would match,
>> as intended - but I would not be able to retrieve the accented version
>> without re-implementing the class behavior.
>
> Interesting example, thanks.
>