[Python-Dev] PEP 455: TransformDict

[Ryan Gonzalez]

100% disagreement. Err, well, 50%.

A property of existing dictionaries is useless. A separate object in, say,
collections is more organized.

3rd party libraries can be hard to find, even the great ones.


On Mon, Oct 7, 2013 at 3:01 PM, Russell E. Owen <rowen at uw.edu> wrote:

> In article <C4C036B6-130C-4718-BEB1-A7C9230082F4 at gmail.com>,
>  Raymond Hettinger <raymond.hettinger at gmail.com> wrote:
>
> > On Sep 22, 2013, at 6:16 PM, Ethan Furman <ethan at stoneleaf.us> wrote:
> >
> > > Are we close to asking for pronouncement?
> >
> > When you're ready, let me know.
> >
> > In the meantime, I conducting usability tests on students in Python
> classes
> > and researching how well it substitutes for existing solutions for
> > case insensitive dictionaries (the primary use case) and for other
> > existing cases such as dictionaries with unicode normalized keys.
> >
> > If you want to participate in the research, I could also use help looking
> > at what other languages do.  Python is not the first language with
> > mappings or to encounter use cases for transforming keys prior
> > to insertion and lookup.   I would like to find out what work has
> > already been done on this problem.
> >
> > Another consideration is whether the problem is more general
> > that just dictionaries.  Would you want similar functionality in
> > all mapping-like objects (i.e. a persistent dictionaries, os.environ,
> etc)?
> > Would you want similar functionality for other services
> > (i.e. case-insensitive filenames or other homomorphisms).
> >
> > You can also add to the discussion by trying out your own usability
> > tests on people who haven't been exposed to this thread or the pep.
> >
> > My early results indicate that the API still needs work.
> >
> >...
> > * Another issue is that we're accumulating too many dictionary
> > variants and that is making it difficult to differentiate and choose
> > between them.  I haven't found anyone (even in advanced classes
> > with very experienced pythonistas) would knew about
> > all the variations:  dict, defaultdict, Mapping, MutableMapping,
> > mapping views, OrderedDict, Counter, ChainMap, andTransformDict.
>
> I agree.
>
> I personally think being able to transform keys would be much more
> useful as a property of existing dictionaries. I often use
> case-insensitive keys. But I use them with dict and OrderedDict (and
> probably ought to use defaultdict, as well).
>
> TransformDict is neat, but I'd personally be happier seeing this as a
> 3rd party library for now.
>
> -- Russell
>
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-- 
Ryan
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