On Tue, Mar 16, 2021 at 9:23 AM Eric V. Smith <e...@trueblade.com> wrote:
> On 3/16/2021 7:01 AM, Simão Afonso @ Powertools Tech wrote:
> >> The problem is that if you have 1 normal parameter and 10 keyword-only
> >> ones, you'd be forced to say:
> >>
> >> @dataclasses.dataclass
> >> class LotsOfFields:
> >> a: Any
> >> b: Any = field(kw_only=True, default=0)
> >> c: Any = field(kw_only=True, default='foo')
> >> d: Any = field(kw_only=True)
> >> e: Any = field(kw_only=True, default=0.0)
> >> f: Any = field(kw_only=True)
> >> g: Any = field(kw_only=True, default=())
> >> h: Any = field(kw_only=True, default='bar')
> >> i: Any = field(kw_only=True, default=3+4j)
> >> j: Any = field(kw_only=True, default=10)
> >> k: Any = field(kw_only=True)
> >>
> >> That's way too verbose for me.
>
Here's another option I just thought of, that might have some strengths:
@dataclasses.dataclass
class LotsOfFields:
# first member assumed to be kw_or_posit unless marked otherwise
a: Any
# start kw only here because `mark= dataclasses.KW_ONLY`
b: Any = field(default=0, mark=dataclasses.KW_ONLY)
# all members following above line continue to be kw_only
c: Any = 'foo'
d: Any
e: Any = 0.0
f: Any
g: Any = ()
h: Any = 'bar'
i: Any = 3+4j
j: Any = 10
k: Any
I changed the kw argument name from `kw_only` to `mark`.
The idea is that every supplied member (above, members c through k) is
assumed to have the same `mark` as the most recently explicitly designated
field (above, member b). Or, if there has not yet been an explicitly
designated `mark` for a member, the first field (above, member a) is
assumed to be `dataclasses.KW_OR_POSIT` (or whatever other singleton name
makes sense).
In this way we only have to use the field() call once, we can go back and
forth, we eliminate a line like `_: dataclasses.KW_OPTIONAL` that to some
people might be a bit inscrutable, and we leave the door open to support
positional arguments in the future (perhaps through something like `mark=
dataclasses.KW_OR_POSIT`) if it becomes desirable for some reason.
---
Ricky.
"I've never met a Kentucky man who wasn't either thinking about going home
or actually going home." - Happy Chandler
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