[Python-Dev] Impact of Namedtuple on startup time (original) (raw)

Tim Peters tim.peters at gmail.com
Mon Jul 17 17:24:17 EDT 2017

[Giampaolo Rodola' <g.rodola at gmail.com>]

.... To be entirely honest, I'm not even sure why they need to be forcefully declared upfront in the first place, instead of just having a first-class function (builtin?) written in C:

>>> ntuple(x=1, y=0) (x=1, y=0) ...or even a literal as in: >>> (x=1, y=0) (x=1, y=0)

How do you propose that the resulting object T know that T.x is 1. T.y is 0, and T.z doesn't make sense? Declaring a namedtuple up front allows the class to know that all of its instances map attribute "x" to index 0 and attribute "y" to index 1. The instances know nothing about that on their own, and consume no more memory than a plain tuple. If your ntuple() returns an object implementing its own mapping, it loses a primary advantage (0 memory overhead) of namedtuples.

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