bpo-38659: [Enum] add _simple_enum decorator (GH-25497)
add:
* `_simple_enum` decorator to transform a normal class into an enum
* `_test_simple_enum` function to compare
* `_old_convert_` to enable checking `_convert_` generated enums
`_simple_enum` takes a normal class and converts it into an enum:
@simple_enum(Enum)
class Color:
RED = 1
GREEN = 2
BLUE = 3
`_old_convert_` works much like` _convert_` does, using the original logic:
# in a test file
import socket, enum
CheckedAddressFamily = enum._old_convert_(
enum.IntEnum, 'AddressFamily', 'socket',
lambda C: C.isupper() and C.startswith('AF_'),
source=_socket,
)
`_test_simple_enum` takes a traditional enum and a simple enum and
compares the two:
# in the REPL or the same module as Color
class CheckedColor(Enum):
RED = 1
GREEN = 2
BLUE = 3
_test_simple_enum(CheckedColor, Color)
_test_simple_enum(CheckedAddressFamily, socket.AddressFamily)
Any important differences will raise a TypeErrordiff --git a/Lib/ast.py b/Lib/ast.py
index e46ab43..703f68a 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -27,7 +27,7 @@
import sys
from _ast import *
from contextlib import contextmanager, nullcontext
-from enum import IntEnum, auto
+from enum import IntEnum, auto, _simple_enum
def parse(source, filename='<unknown>', mode='exec', *,
@@ -636,7 +636,8 @@ class Param(expr_context):
# We unparse those infinities to INFSTR.
_INFSTR = "1e" + repr(sys.float_info.max_10_exp + 1)
-class _Precedence(IntEnum):
+@_simple_enum(IntEnum)
+class _Precedence:
"""Precedence table that originated from python grammar."""
TUPLE = auto()