Missing import in example at dataclasses.rst

[xandrade]

Documentation

Found that the typing List is used in example, but import is missed at dataclasses.rst file.

In this example:

  @dataclass
  class D:
      x: List = []
      def add(self, element):
          self.x += element

the import from typing import List is missing

[ericvsmith]

I'm not sure how important this is. The example already says the code isn't valid. Maybe just use "list" instead of "List".

[xandrade]

Sure @ericvsmith, but the example in the documentation doesn't run.
Your suggestion for using list instead of list works, as long it is defined as x: list = field(default_factory=list).
However, I think the example is about forcing the datatype in the list using List from typing.

This works (as example only):

from dataclasses import dataclass
from typing import List

@dataclass
class User:
    x: list = field(default_factory=list)
    y: List[int] = field(default_factory=list)

this doesn't work

from dataclasses import dataclass

@dataclass
class User:
    x: list = []