[issue45972] typing.NamedTuple with default arguments without type annotations is falsy

[Erik Montnemery]

Erik Montnemery <erik at montnemery.com> added the comment:

Maybe something like this:

diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst
index 735d477db4..8de913d8db 100644
--- a/Doc/library/typing.rst
+++ b/Doc/library/typing.rst
@@ -1291,7 +1291,8 @@ These are not used in annotations. They are building blocks for declaring types.

 .. class:: NamedTuple

-   Typed version of :func:`collections.namedtuple`.
+   Typed version of :func:`collections.namedtuple`, annotated fields are passed
+   to an underlying `collections.namedtuple`.

    Usage::

@@ -1311,9 +1312,20 @@ These are not used in annotations. They are building blocks for declaring types.

       employee = Employee('Guido')
       assert employee.id == 3
+      assert employee == ('Guido', 3)

    Fields with a default value must come after any fields without a default.

+   Non-annotated fields will not be part of the `collections.namedtuple`::
+
+      class Employee(NamedTuple):
+          name = 'Guido'
+          id = 3
+
+      employee = Employee()
+      assert employee.id == 3
+      assert not employee  # Passes because the collections.namedtuple is empty
+
    The resulting class has an extra attribute ``__annotations__`` giving a
    dict that maps the field names to the field types.  (The field names are in

----------

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue45972>
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