[Python-Dev] PEP 435 - ref impl disc 2

Ethan Furman ethan at stoneleaf.us
Tue May 7 03:26:56 CEST 2013

On 05/05/2013 01:01 AM, Glenn Linderman wrote:
> The bigger problem is that the arithmetic on enumeration items, which seems like it should be inherited from NamedInt
> (and seems to be, because the third value from each print is a NamedInt), doesn't pick up "x" or "y", nor does it pick
> up "the-x" or "the-y", but rather, it somehow picks up the str of the value.

Indeed, the bigger problem is that we ended up have an (NamedInt, Enum) wrapping a NamedInt, so we had both 
NEI.x._intname /and/ NEI.x.value._intname, and it was just one big mess.

But I think it is solved.  Try the new code.  Here's what your example should look like:

     class NamedInt( int ):
         def __new__( cls, *args, **kwds ):
             _args = args
             name, *args = args
             if len( args ) == 0:
                 raise TypeError("name and value must be specified")
             self = int.__new__( cls, *args, **kwds )
             self._intname = name
             return self
         def __name__( self ):
             return self._intname
         def __repr__( self ):
             # repr() is updated to include the name and type info
             return "{}({!r}, {})".format(type(self).__name__,
         def __str__( self ):
             # str() is unchanged, even if it relies on the repr() fallback
             base = int
             base_str = base.__str__
             if base_str.__objclass__ is object:
                 return base.__repr__(self)
             return base_str(self)
         # for testing, we only define one operator that propagates expressions
         def __add__(self, other):
             temp = int( self ) + int( other )
             if isinstance( self, NamedInt ) and isinstance( other, NamedInt ):
                 return NamedInt(
                     '({0} + {1})'.format(self.__name__, other.__name__),
                     temp )
                 return temp

     class NEI( NamedInt, Enum ):
         x = ('the-x', 1 )
         y = ('the-y', 2 )

     NEI.x + NEI.y


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