On Tue, Oct 08, 2019 at 12:55:40PM -0400, Todd wrote:
> > da.isel(space=0, time=slice(None, 2))[...] = spam
> >
> > With this syntax this could be changed to:
> >
> > da[space=0, time=:2] = spam
> >
Anders:
> > I must have missed something... when did the proposal we're discussing
> > start allowing : there?
Todd:
> Why wouldn't it?
Wrong question. New features are not "default accept", we accept them
unless there is a strong reason to reject them. They are "default
reject", we reject them unless there is a good reason to accept them. So
the right question is, why should we accept colons there?
This is a proposal for adding keyword args to subscripting, not
colon-syntax for slice objects inside arbitrary expressions. If you wish
to propose that, you can propose it separately.
But for the record, here is one reason why we probably should not allow
`time=:2` as syntactic sugar for `time=slice(None, 2)`.
It is confusing as hell. When I saw this
da[space=0, time=:2]
I read it as a slice:
da[ slice( (space=0, time=), 2, None) ]
and thought "That must be a typo, because the time keyword
doesn't have a value."
And combining slice syntax with keywords in the same call is a recipe
for over-complicated, confusing subscripts, which is why Caleb initially
suggested you can use one, or the other, but not both.
--
Steven
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