[Python-ideas] namedtuple literals [Was: RE a new namedtuple]

Nick Coghlan ncoghlan at gmail.com
Sun Jul 30 11:24:12 EDT 2017

On 30 July 2017 at 20:03, Alex Walters <tritium-list at sdamon.com> wrote:
>> -----Original Message-----
>> From: Python-ideas [mailto:python-ideas-bounces+tritium-
>> list=sdamon.com at python.org] On Behalf Of Michel Desmoulin
>> Sent: Sunday, July 30, 2017 4:19 AM
>> To: python-ideas at python.org
>> Subject: Re: [Python-ideas] namedtuple literals [Was: RE a new namedtuple]
>> Le 29/07/2017 à 18:14, Alex Walters a écrit :
>> > My $0.02 on the entire series of nametuple threads is… there **might**
>> > be value in an immutable namespace type, and a mutable namespace type,
>> > but namedtuple’s promise is that they can be used anywhere a tuple can
>> > be used.  If passing in kwargs to create the potential replacement to
>> > namedtuple is sensitive to dict iteration order, it really isn’t a
>> > viable replacement for namedtuple.
>> In Python 3.6, kwargs order is preserved and guaranteed. It's currently
>> implemented by relying on the non guaranteed dict order. But the 2 are
>> not linked. The spec does guaranty that for now on, kwargs order is
>> always preserved whether the dict order is or not.
> MyNT = namedtuple_replacement('MyNT', 'foo bar')
> data = {}
> data['bar'] = 8675309
> data['foo'] = 525600
> MyNT(*data) == (525600, 8675309)   # better be true, or else, we are depending on iteration order.

Did you mean "MyNT(**data)" in the last line?

Either way, this is just normal predefined namedtuple creation, where
the field order is set when the type is defined.

Rather than being about any changes on that front, these threads are
mostly about making it possible to write that first line as:

    MyNT = type(implicitly_typed_named_tuple_factory(foo=None, bar=None))

(While they do occasionally veer into discussing the idea of
yet-another-kind-of-data-storage-type, that is an extraordinarily
unlikely outcome)


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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