[Python-ideas] Enums

[Nick Coghlan]

On Thu, Jul 28, 2011 at 10:56 AM, Barry Warsaw <barry at python.org> wrote:
> Again, looking at how I've used them extensively over the last several years,
> I would much rather write
>
>    class Colors(Enum):
>        red = 1
>        green = 2
>        blue = 3
>
> than
>
>    red = NamedValue('red', 1)
>    green = NamedValue('green', 2)
>    blue = NamedValue('blue', 3)
>
> To me, the duplication is jarring and error prone.

Yeah, I'd actually be inclined to define such values programmatically
rather than writing them out manually like that:

_named_colours = dict(
  red=0xFF0000,
  green=0x00FF00,
  blue=0x0000FF,
)
globals().update((k, namedvalue(k, v)) for k, v in _named_colours)

(where namedvalue is the value based factory function I mentioned in
the recipe post)

However, my contention is that the fundamentally interesting operation
is associating names with values (as your EnumValue class does). Enums
and their ilk are then just syntactic sugar for defining groups of
such values without needing to repeat yourself.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia