issue23673

add private method to enum to support replacing global constants with Enum members:
- search for candidate constants via supplied filter
- create new enum class and members
- insert enum class and replace constants with members via supplied module name
- replace __reduce_ex__ with function that returns member name, so previous Python versions can unpickle
modify IntEnum classes to use new method

1 files changed, 26 insertions, 0 deletions

diff --git a/Lib/enum.py b/Lib/enum.py
index 5be13d5c71..1d9ebf0f94 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -519,11 +519,37 @@ class Enum(metaclass=EnumMeta):
         """The value of the Enum member."""
         return self._value_
 
+    @classmethod
+    def _convert(cls, name, module, filter, source=None):
+        """
+        Create a new Enum subclass that replaces a collection of global constants
+        """
+        # convert all constants from source (or module) that pass filter() to
+        # a new Enum called name, and export the enum and its members back to
+        # module;
+        # also, replace the __reduce_ex__ method so unpickling works in
+        # previous Python versions
+        module_globals = vars(sys.modules[module])
+        if source:
+            source = vars(source)
+        else:
+            source = module_globals
+        members = {name: value for name, value in source.items()
+                if filter(name)}
+        cls = cls(name, members, module=module)
+        cls.__reduce_ex__ = _reduce_ex_by_name
+        module_globals.update(cls.__members__)
+        module_globals[name] = cls
+        return cls
+
 
 class IntEnum(int, Enum):
     """Enum where members are also (and must be) ints"""
 
 
+def _reduce_ex_by_name(self, proto):
+    return self.name
+
 def unique(enumeration):
     """Class decorator for enumerations ensuring unique member values."""
     duplicates = []