bpo-40066: [Enum] update str() and format() output (GH-30582)

Undo rejected PEP-663 changes:

- restore `repr()` to its 3.10 status
- restore `str()` to its 3.10 status

New changes:

- `IntEnum` and `IntFlag` now leave `__str__` as the original `int.__str__` so that str() and format() return the same result
- zero-valued flags without a name have a slightly changed repr(), e.g. `repr(Color(0)) == '<Color: 0>'`
- update `dir()` for mixed-in types to return all the methods and attributes of the mixed-in type
- added `_numeric_repr_` to `Flag` to control display of unnamed values
- enums without doc strings have a more comprehensive doc string added
- `ReprEnum` added -- inheriting from this makes it so only `__repr__` is replaced, not `__str__` nor `__format__`; `IntEnum`, `IntFlag`, and `StrEnum` all inherit from `ReprEnum`

Author: ethanfurman

Doc/howto/enum.rst

@@ -2070,7 +2070,7 @@ to speed up repeated connections from the same clients.
       :attr:`SSLContext.verify_flags` returns :class:`VerifyFlags` flags:
 
          >>> ssl.create_default_context().verify_flags  # doctest: +SKIP
-         ssl.VERIFY_X509_TRUSTED_FIRST
+         <VerifyFlags.VERIFY_X509_TRUSTED_FIRST: 32768>
 
 .. attribute:: SSLContext.verify_mode
 
@@ -2082,7 +2082,7 @@ to speed up repeated connections from the same clients.
       :attr:`SSLContext.verify_mode` returns :class:`VerifyMode` enum:
 
          >>> ssl.create_default_context().verify_mode
-         ssl.CERT_REQUIRED
+         <VerifyMode.CERT_REQUIRED: 2>
 
 .. index:: single: certificates
 

Doc/library/enum.rst

@@ -2567,30 +2567,28 @@ class _empty:
 
 
 class _ParameterKind(enum.IntEnum):
-    POSITIONAL_ONLY = 0
-    POSITIONAL_OR_KEYWORD = 1
-    VAR_POSITIONAL = 2
-    KEYWORD_ONLY = 3
-    VAR_KEYWORD = 4
+    POSITIONAL_ONLY = 'positional-only'
+    POSITIONAL_OR_KEYWORD = 'positional or keyword'
+    VAR_POSITIONAL = 'variadic positional'
+    KEYWORD_ONLY = 'keyword-only'
+    VAR_KEYWORD = 'variadic keyword'
+
+    def __new__(cls, description):
+        value = len(cls.__members__)
+        member = int.__new__(cls, value)
+        member._value_ = value
+        member.description = description
+        return member
 
-    @property
-    def description(self):
-        return _PARAM_NAME_MAPPING[self]
+    def __str__(self):
+        return self.name
 
 _POSITIONAL_ONLY         = _ParameterKind.POSITIONAL_ONLY
 _POSITIONAL_OR_KEYWORD   = _ParameterKind.POSITIONAL_OR_KEYWORD
 _VAR_POSITIONAL          = _ParameterKind.VAR_POSITIONAL
 _KEYWORD_ONLY            = _ParameterKind.KEYWORD_ONLY
 _VAR_KEYWORD             = _ParameterKind.VAR_KEYWORD
 
-_PARAM_NAME_MAPPING = {
-    _POSITIONAL_ONLY: 'positional-only',
-    _POSITIONAL_OR_KEYWORD: 'positional or keyword',
-    _VAR_POSITIONAL: 'variadic positional',
-    _KEYWORD_ONLY: 'keyword-only',
-    _VAR_KEYWORD: 'variadic keyword'
-}
-
 
 class Parameter:
     """Represents a parameter in a function signature.

Doc/library/ssl.rst

@@ -61,7 +61,8 @@
 from xml.parsers.expat import ParserCreate
 
 
-PlistFormat = enum.global_enum(enum.Enum('PlistFormat', 'FMT_XML FMT_BINARY', module=__name__))
+PlistFormat = enum.Enum('PlistFormat', 'FMT_XML FMT_BINARY', module=__name__)
+globals().update(PlistFormat.__members__)
 
 
 class UID:

Lib/enum.py

@@ -155,6 +155,8 @@ class RegexFlag:
     # sre extensions (experimental, don't rely on these)
     TEMPLATE = T = sre_compile.SRE_FLAG_TEMPLATE # disable backtracking
     DEBUG = sre_compile.SRE_FLAG_DEBUG # dump pattern after compilation
+    __str__ = object.__str__
+    _numeric_repr_ = hex
 
 # sre exception
 error = sre_compile.error

Lib/inspect.py

@@ -119,7 +119,6 @@
 )
 from _ssl import _DEFAULT_CIPHERS, _OPENSSL_API_VERSION
 
-
 _IntEnum._convert_(
     '_SSLMethod', __name__,
     lambda name: name.startswith('PROTOCOL_') and name != 'PROTOCOL_SSLv23',