[swift-evolution] Optional assignment operator

[Trent Nadeau]

This same operator (except spelled as ??=) was up as a proposal and
rejected in February. See
http://thread.gmane.org/gmane.comp.lang.swift.evolution/7694.

On Thu, May 12, 2016 at 10:41 AM, Rod Brown via swift-evolution <
swift-evolution at swift.org> wrote:

> I’m tentatively supportive of this proposal. I definitely see the use case
> (assign only if not not nil).  Interested to hear the opinions of others
> here :)
>
> -Rod
>
>
> > On 12 May 2016, at 11:59 PM, Jose Manuel Sánchez Peñarroja via
> swift-evolution <swift-evolution at swift.org> wrote:
> >
> > Sorry if this has already been discussed, if so I couldn’t find it.
> >
> > I would like to propose to add to Swift an optional assignment operator
> ?=
> > I think this would nicely align with the other uses of ?, and avoid
> repetition in this case:
> >
> >       var value = 5
> >
> >       var possibleNewValue: Int? = nil
> >
> >       value = possibleNewValue ?? value
> >
> > It would be used like this:
> >
> >       value ?= possibleNewValue
> >
> > I’ve found quite a few cases in which this would be very useful to me.
> It is already possible to implement it, but having it defined in the
> standard library would define an standard, and prevent different semantics
> depending on who implements it.
> >
> >
> >       infix operator ?= {
> >         associativity right
> >          precedence 90
> >          assignment
> >       }
> >
> >       func ?= <T>(inout lhs: T, rhs: T?) {
> >           lhs = rhs ?? lhs
> >       }
> >
> >
> > Regards,
> > José Manuel Sanchez
> > _______________________________________________
> > swift-evolution mailing list
> > swift-evolution at swift.org
> > https://lists.swift.org/mailman/listinfo/swift-evolution
>
> _______________________________________________
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>



-- 
Trent Nadeau
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