Cameron Simpson writes:
> On 08Nov2021 23:32, MRAB <pyt...@mrabarnett.plus.com> wrote:
> >A flag could be a member, but could a set of flags?
>
> Probably one flavour should raise a TypeError then with this comparison.
> I wouldn't want "member flag present in SomeFlag.something" and
> "set-of-members present in SomeFlag.something" to both be valid,
If the latter is valid, so is the former, since "member flag" is
representable as "singleton containing member flag". (I think this
representation of sets of flags is the primary use case for IntFlag,
as opposed to Flag or IntEnum.) If I really needed to distinguish, I
wouldn't use a Enum type that can represent multiple members in one
item, I'd use Python sets of Flags, .
> I would rather punt the "set-of-members present" off to "<"/"<=" if
> we want to say either (which of course we should be able to say).
<MyFlag.1> < <MyFlag.2> == True since IntFlag is derived from int, but
that's not what we want. You'd have to define __lt__ for every such
flag type. For convenience, we would want a new Enum type in the
stdlib.
> Of course, I think resently we don't distinguish a flag combination
> name (".nothing", ".red_and_blue"==0b11) from single flags
> overtly.
I think we really don't want to do that in the stdlib. Such flags
would often support operations like intersection and set difference
that could easily result in singletons, which then might be checked
against an "allow set". If you care about the distinction between
singleton-representing-element and other sets of flags, elements of
the flag enum and sets of those elements need to be different types.
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