[swift-evolution] Re-pitch: remove(where:)

[Xiaodi Wu]

On Tue, Sep 26, 2017 at 6:14 PM, Ben Cohen via swift-evolution <
swift-evolution at swift.org> wrote:

> And here are my answers, in a separate email to maintain a shred of
> separation between objectivity and subjectivity :)
>
> > On Sep 26, 2017, at 4:12 PM, Ben Cohen via swift-evolution <
> swift-evolution at swift.org> wrote:
> >
> > 1. Is it right to assert that with a “removing” operation, the closure
> should return `true` for removal?
>
> Yes. If the closure returned false for removal a different, less readable,
> name would be needed for the method.
>

Agree, yes.

> 2. Is it likely that users will want to switch from out-of- to in-place,
> and if so, will having to flip the closure cause confusion/bugs?
>
> I don’t think so. While the argument for an in-place remove is partly that
> it’s more efficient than x = x.filter (in addition to
> reability/discoverability benefits), I think that once both an in- and
> out-of-place version are available, users will reach immediately for the
> one they want. The scenario where you were filtering, and then you realize
> you could do it in-place more efficiently, doesn’t seem to me like it will
> come up in day-to-day use.
>

Unsure. Maybe and maybe, but I think the confusion/bugs would be limited if
the full matrix of four operations exist.


> > 3. Should we “complete” the matrix of 4 operations, or is it fine for it
> to have gaps?
>
> I think filter(_:) and remove(where:) are sufficient. I don’t think we
> need to complete the set.


Based on question (2), I would argue that the answer is yes.

> 4. If you are for completing, what should X and Y be called?
> >
>
> One of the reasons I _don’t_ think we should complete the set is that
> formFilter(_:) will take us into serious jumped-the-shark territory,
> naming-wise.
>
> I think there’s an argument for never having had filter, and always having
> had remove/removed (or possibly select/selected), but don’t think this is
> important enough to clear the bar for a rename of this magnitude.


IMO, they should be called removing(where:) [removed(where:) reads weirdly
in conjunction with the preceding receiver] and formFilter(_:). Hundreds of
messages finally settled on "form" as the in-place verb of choice where the
noun can't ordinarily be verbed. No point in being shy about it now: that's
the Swift way, wear it proudly.
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