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

[Antoine Pitrou]

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 -

Well, it is not here for dict, set, etc.

> 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.

Regards

Antoine.