Consider following piece of code:
from collections import namedtuple
point = namedtuple("Point", ("x:int", "y:int"))
The Code above is just a way to demonstrate as to what I am trying to achieve.
I would like to make namedtuple with type hints.
Do you know any elegant way how to achieve result as intended?
The preferred syntax for a typed namedtuple since Python 3.6 is using typing.NamedTuple like so:
from typing import NamedTuple
class Point(NamedTuple):
x: int
y: int = 1 # Set default value
Point(3) # -> Point(x=3, y=1)
Starting with Python 3.7, consider using a dataclasses:
from dataclasses import dataclass
@dataclass
class Point:
x: int
y: int = 1 # Set default value
Point(3) # -> Point(x=3, y=1)
You can use typing.NamedTuple
From the docs
Typed version of
namedtuple.
>>> import typing
>>> Point = typing.NamedTuple("Point", [('x', int), ('y', int)])
This is present only in Python 3.5 onwards
Point = typing.NamedTuple("Point", x=int, y=int), which is much cleaner and shorter.
(tags/v3.10.9:1dd9be6)), it was removed from the docstrings in pull 105287 because according to the pull author, "this way of creating NamedTuples isn't supported by any [known] type checker".Just to be fair, NamedTuple from typing:
>>> from typing import NamedTuple
>>> class Point(NamedTuple):
... x: int
... y: int = 1 # Set default value
...
>>> Point(3)
Point(x=3, y=1)
equals to classic namedtuple:
>>> from collections import namedtuple
>>> p = namedtuple('Point', 'x,y', defaults=(1, ))
>>> p.__annotations__ = {'x': int, 'y': int}
>>> p(3)
Point(x=3, y=1)
So, NamedTuple is just syntax sugar for namedtuple
Below, you can find a creating NamedTuple function from the source code of python 3.10. As we can see, it uses collections.namedtuple constructor and adds __annotations__ from extracted types:
def _make_nmtuple(name, types, module, defaults = ()):
fields = [n for n, t in types]
types = {n: _type_check(t, f"field {n} annotation must be a type")
for n, t in types}
nm_tpl = collections.namedtuple(name, fields,
defaults=defaults, module=module)
nm_tpl.__annotations__ = nm_tpl.__new__.__annotations__ = types
return nm_tpl
NamedTuple is a bit more complicated than that, being a function that actually does something at runtime.
__annotations__ attr of just created namedtuple using constructor collections.namedtuple. I added that code to the answer for better understanding.