bpo-36320: Switch typing.NamedTuple from OrderedDict to regular dict (GH-12396)
Also, deprecate the *_field_types* attributes which duplicated the information in *\__annotations__*.
https://bugs.python.org/issue36320
diff --git a/Lib/typing.py b/Lib/typing.py
index 3243e2a..530d463 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1325,8 +1325,8 @@
types = [(n, _type_check(t, msg)) for n, t in types]
nm_tpl = collections.namedtuple(name, [n for n, t in types])
# Prior to PEP 526, only _field_types attribute was assigned.
- # Now, both __annotations__ and _field_types are used to maintain compatibility.
- nm_tpl.__annotations__ = nm_tpl._field_types = collections.OrderedDict(types)
+ # Now __annotations__ are used and _field_types is deprecated (remove in 3.9)
+ nm_tpl.__annotations__ = nm_tpl._field_types = dict(types)
try:
nm_tpl.__module__ = sys._getframe(2).f_globals.get('__name__', '__main__')
except (AttributeError, ValueError):
@@ -1361,7 +1361,7 @@
"follow default field(s) {default_names}"
.format(field_name=field_name,
default_names=', '.join(defaults_dict.keys())))
- nm_tpl.__new__.__annotations__ = collections.OrderedDict(types)
+ nm_tpl.__new__.__annotations__ = dict(types)
nm_tpl.__new__.__defaults__ = tuple(defaults)
nm_tpl._field_defaults = defaults_dict
# update from user namespace without overriding special namedtuple attributes
@@ -1386,12 +1386,10 @@
Employee = collections.namedtuple('Employee', ['name', 'id'])
- The resulting class has extra __annotations__ and _field_types
- attributes, giving an ordered dict mapping field names to types.
- __annotations__ should be preferred, while _field_types
- is kept to maintain pre PEP 526 compatibility. (The field names
- are in the _fields attribute, which is part of the namedtuple
- API.) Alternative equivalent keyword syntax is also accepted::
+ The resulting class has an extra __annotations__ attribute, giving a
+ dict that maps field names to types. (The field names are also in
+ the _fields attribute, which is part of the namedtuple API.)
+ Alternative equivalent keyword syntax is also accepted::
Employee = NamedTuple('Employee', name=str, id=int)