[swift-evolution] [swift-evolution-announce] [Review] SE-0024 "Optional Value Setter `??=`"

[Ross O'Brien]

"y is assigned to x if x is nil" *is* exactly what "x ??= y" means. If x is
nil, x is assigned the value of y; if x is not nil, it doesn't matter what
y is.

This is exactly consistent with the boolean operator ||= ; "x ||= y" means
"y is assigned to x if x is false" - if x is false, x is assigned the value
of y; if x is true, it doesn't matter what y is.)

Why do you think it means the opposite?

On Tue, Feb 16, 2016 at 1:24 PM, David Sweeris via swift-evolution <
swift-evolution at swift.org> wrote:

> -1, because in my mind, "x ??= y" kinda looks like "y is assigned to x iff
> y isn't nil", or, if you associate the ?? part with the lhs, "y is assigned
> to x if x is nil", neither of which is what the proposed operator means. In
> fact, the 2nd case is the *opposite* of what ??= means in this proposal.
>
> To be clear, it's the syntax that I'm opposed to, not the concept.
>
> - Dave Sweeris
>
> On Feb 12, 2016, at 23:15, Douglas Gregor <dgregor at apple.com> wrote:
>
> Hello Swift community,
>
> The review of SE-0024 "Optional Value Setter `??=`" begins now and runs
> through February 18, 2016. The proposal is available here:
>
>
> https://github.com/apple/swift-evolution/blob/master/proposals/0024-optional-value-setter.md
>
> Reviews are an important part of the Swift evolution process. All reviews
> should be sent to the swift-evolution mailing list at
>
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
> or, if you would like to keep your feedback private, directly to the
> review manager. When replying, please try to keep the proposal link at the
> top of the message:
>
> Proposal link:
>
>
> https://github.com/apple/swift-evolution/blob/master/proposals/0024-optional-value-setter.md
>
> Reply text
>
> Other replies
>
> <https://github.com/apple/swift-evolution#what-goes-into-a-review-1>What
> goes into a review?
>
> The goal of the review process is to improve the proposal under review
> through constructive criticism and, eventually, determine the direction of
> Swift. When writing your review, here are some questions you might want to
> answer in your review:
>
>    - What is your evaluation of the proposal?
>    - Is the problem being addressed significant enough to warrant a
>    change to Swift?
>    - Does this proposal fit well with the feel and direction of Swift?
>    - If you have used other languages or libraries with a similar
>    feature, how do you feel that this proposal compares to those?
>    - How much effort did you put into your review? A glance, a quick
>    reading, or an in-depth study?
>
> More information about the Swift evolution process is available at
>
> https://github.com/apple/swift-evolution/blob/master/process.md
>
> Thank you,
>
> Doug Gregor
>
> Review Manager
>
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