[Python-ideas] another enum implementation

[Yury Selivanov]

I'm not sure why, but I didn't see anyone making a point about
documentation.  To me, it's important that stdlib's and other
libraries' enums are well documented, and I think that the best
way of providing and enforcing this is to mimic "property" builtin.

class Color(enum.Sequence):
   "Some general docs about Color enum"
   BLACK = enum.value(doc='Black Color')

or

class Color(enum.Flag):
   "..."
   BLACK = enum(doc='Black Color')
   WHITE = enum()

Maybe this is uglier than magic of just writing flags' names,
but this implementation is much simpler, backwards compatible with
python 2, and verbose.  The latter point is both good and bad, but
we don't write enums that often to make a bit of verbosity unacceptable.

Just my two cents.

-
Yury

On 2013-02-13, at 12:04 AM, Ethan Furman <ethan at stoneleaf.us> wrote:

> I realize this isn't going very far, but I would still appreciate feedback.  :)
> 
> The code is here:
> https://bitbucket.org/stoneleaf/enum
> 
> It is based on ideas from Michael Foord, Antoine Pitrou, and (eventually) Ted Delaney.
> 
> 
> Enum only accepts upper-case names as enum candidates; all enum values must be the same: either 'sequence' (0, 1, 2, etc) or 'flag' (1, 2, 4, etc.) or 'unique' (north, south, east, west, etc.); and extending via subclassing is possible.
> 
> Sample code:
> 
> class Color(Enum):
>    type = 'sequence'
>    BLACK
>    RED
>    GREEN = 4
>    BLUE
> print Color
> # Color(BLACK:0, RED:1, GREEN:4, BLUE:5)
> 
> class MoreColor(Color):
>    MAGENTA
>    YELLOW
>    CYAN
> print MoreColor
> # MoreColor(BLACK:0, RED:1, GREEN:4, BLUE:5, MAGENTA:6, YELLOW:7,
> #	    CYAN:8)
> 
> 
> class DbfType(Enum):
>    type = 'unique'
>    CLP
>    DB3
>    VFP
> --> print(enum.DbfType)
> # DbfType(DB3:'db3', CLP:'clp', VFP:'vfp')
> 
> class SomeFlags(Enum):
>    type = 'flag'
>    ON_DISK
>    HAS_MEMO
>    LARGE_CHAR
>    UNICODE
> --> print(enum.SomeFlags)
> # SomeFlags(ON_DISK:1, HAS_MEMO:2, LARGE_CHAR:4, UNICODE:8)
> 
> class Error(Enum):
>    type = 'sequence'
>    THIS
>    THAT
>    The_Other		# raises NameError
>    THOSE = 1		# raises InvalidEnum
> 
> -->enum.Color.RED
> Color('RED')
> 
> -->enum.Color.RED == 1
> True
> 
> -->int(enum.Color.RED)
> 1
> 
> -->enum.SomeFlags.ON_DISK
> SomeFlags('ON_DISK')
> 
> -->enum.SomeFlags.ON_DISK == 1
> True
> 
> -->int(enum.SomeFlags.ON_DISK)
> 1
> 
> -->enum.SomeFlags.ON_DISK == enum.Color.RED
> False
> 
> -->enum.MoreColor.RED == 1
> True
> 
> -->enum.MoreColor.RED == enum.Color.RED
> True
> 
> -->enum.Color(1)
> Color('RED')
> 
> -->enum.Color('RED')
> Color('RED')
> 
> --> for color in enum.Color:
> ...   print(color)
> ...
> BLACK
> RED
> GREEN
> BLUE
> 
> --> for color in enum.Color:
> ...   print(repr(color))
> ...
> Color('BLACK')
> Color('RED')
> Color('GREEN')
> Color('BLUE')
> 
> 
> I would appreciate any comments on both the API, and the code behind it.
> 
> Thanks.
> 
> --
> ~Ethan~
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