[Python-Dev] PEP 435: initial values must be specified? Yes

Sun May 5 22:09:50 CEST 2013

On 05/05/2013 10:07 AM, � wrote:> I'm chiming in late, but am I the only one who's really bothered by the syntax?
>> class Color(Enum):
> red = 1
> green = 2
> blue = 3

No, you are not only one that's bothered by it. I tried it without assignments until I discovered that bugs are way too 
easy to introduce. The problem is a successful name lookup looks just like a name failure, but of course no error is 
raised and no new enum item is created:
--> class Color(Enum):
... red, green, blue
...
--> class MoreColor(Color):
... red, orange, yellow
...
--> type(MoreColor.red) is MoreColor
False
--> MoreColor.orange
<MoreColor.orange: 4> # value should be 5
About the closest you going to be able to get is something like:
def e(_next=[1]):
 e, _next[0] = _next[0], _next[0] + 1
 return e
class Color(Enum):
 red = e()
 green = e()
 blue = e()
and you can keep using `e()` for all your enumerations, since you don't care what actual value each enumeration member 
happens to get.
--
~Ethan~