bpo-32506: Change dataclasses from OrderedDict to plain dict. (gh-5131)
diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 9e186c3..d800549 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1,7 +1,6 @@
import sys
import types
from copy import deepcopy
-import collections
import inspect
__all__ = ['dataclass',
@@ -448,11 +447,11 @@
def _process_class(cls, repr, eq, order, hash, init, frozen):
- # Use an OrderedDict because:
- # - Order matters!
- # - Derived class fields overwrite base class fields, but the
- # order is defined by the base class, which is found first.
- fields = collections.OrderedDict()
+ # Now that dicts retain insertion order, there's no reason to use
+ # an ordered dict. I am leveraging that ordering here, because
+ # derived class fields overwrite base class fields, but the order
+ # is defined by the base class, which is found first.
+ fields = {}
# Find our base classes in reverse MRO order, and exclude
# ourselves. In reversed order so that more derived classes
@@ -612,7 +611,8 @@
except AttributeError:
raise TypeError('must be called with a dataclass type or instance')
- # Exclude pseudo-fields.
+ # Exclude pseudo-fields. Note that fields is sorted by insertion
+ # order, so the order of the tuple is as the fields were defined.
return tuple(f for f in fields.values() if f._field_type is _FIELD)
@@ -735,7 +735,7 @@
# Copy namespace since we're going to mutate it.
namespace = namespace.copy()
- anns = collections.OrderedDict()
+ anns = {}
for item in fields:
if isinstance(item, str):
name = item