[Python-Dev] AutoNumber Enum (original) (raw)

Guido van Rossum guido at python.org
Wed Jun 29 15:11:39 EDT 2016

And how would you implement that without support from the compiler? Does it use a hook that catches the NameError?

On Wed, Jun 29, 2016 at 11:15 AM, Brett Cannon <brett at python.org> wrote:

On Wed, 29 Jun 2016 at 10:41 Ethan Furman <ethan at stoneleaf.us> wrote:

There is a several-month-old request to add aenum's [1] AutoNumberEnum to the stdlib [2]. The requester and two of the three developers of Enum are in favor (the third hasn't chimed in yet). This new addition would enable the following: from Enum import AutoNumberEnum class Color(AutoNumberEnum): # auto-number magic is on Red Green Blue Cyan # magic turns off when non-enum is defined def isprimary(self): # typos in methods, etc, will raise return self in (self.Red, self.Grene, self.Blue) # typos after the initial definition stanza will raise BlueGreen = Blue + Grene There is, of course, the risk of typos during the initial member definition stanza, but since this magic only happens when the user explicitly asks for it (AutoNumberEnum), I think it is acceptable. The start parameter is still available, and assigning a number is supported (subsequent numbers will (re)start from the assigned number). Thoughts? Opinions? Flames? Is it going to subclass Enum or IntEnum? Personally I would be quite happy to never have to specify a value for enums ever again, but only if they subclass Enum (since IntEnum is for compatibility with C stuff where a specific value is needed I don't think users need to mess that up by having the automatic numbering not work how they would expect).

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