Hmm, yea I had not thought of how it would look - I had thought formost of not needing to necessarily learn about bitsets.when learning about passing a large number of optional flags to a function.

Although the default could be None, interpreted as an empty set of zero values.; a set of one or more enums does use more characters compared to or-ing flags...

On Sunday, 31 December 2017 05:34:23 UTC, Guido van Rossum wrote:

On Sat, Dec 30, 2017 at 8:50 PM, Franklin? Lee <leewangzh...@gmail.com> wrote:

Paddy might want something like this:
- For existing APIs which take int or IntFlag flags, allow them to
also take a set (or perhaps any collection) of flags.
- In new APIs, take sets of Enum flags, and don't make them IntFlag.
- Documentation should show preference toward using sets of Enum
flags. Tutorials should pass sets.

I'm not keen on this recommendation. An argument that takes a Set[Foo] would mean that in order to specify:

- no flags: you'd have to pass set() -- you can't use {} since that's an empty dict, not an empty set

- one flag: you'd have to pass {Foo.BAR} rather than just Foo.BAR

- two flags: you'd have to pass {Foo.BAR, Foo.BAZ} rather than Foo.BAR | Foo.BAZ

I think for each of these the proposal would be strictly worse than the current convention.

--

--Guido van Rossum (python.org/~guido)