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

Todd toddrjen at gmail.com
Sun Jul 23 12:08:03 EDT 2017

On Jul 20, 2017 1:13 AM, "David Mertz" <mertz at gnosis.cx> wrote:

I'm concerned in the proposal about losing access to type information (i.e.
name) in this proposal.  For example, I might write some code like this now:

>>> from collections import namedtuple
>>> Car = namedtuple("Car", "cost hp weight")
>>> Motorcycle = namedtuple("Motorcycle", "cost hp weight")
>>> smart = Car(18_900, 89, 949)
>>> harley = Motorcyle(18_900, 89, 949)
>>> if smart==harley and type(smart)==type(harley):
...     print("These are identical vehicles")

The proposal to define this as:

>>> smart = (cost=18_900, hp=89, weight=949)
>>> harley = (cost=18_900, hp=89, weight=949)

Doesn't seem to leave any way to distinguish the objects of different types
that happen to have the same fields.  Comparing `
smart._fields==harley._fields` doesn't help here, nor does any type
constructed solely from the fields.

What about making a syntax to declare a type? The ones that come to mind are

    name = (x=, y=)


    name = (x=pass, y=pass)

They may not be clear enough, though.
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