Re: [Python-Dev] Rationale for different signatures of tuple.__new__ and namedtuple.__new__

On 02/18/2013 03:32 PM, John Reid wrote:

I can do

tuple([1,2,3])

but not:

from collections import namedtuple namedtuple('B', 'x y z')([1,2,3])

I get a TypeError: __new__() takes exactly 4 arguments (2 given) However I can do:

namedtuple('B', 'x y z')._make([1,2,3])

So namedtuple's _make classmethod looks a lot like tuple's __new__(). What's the rationale for this? Wouldn't it be better to share the same signature for __new__?

Sharing the constructor signature with tuple would break the common case of: namedtuple('B', 'x y z')(1, 2, 3)