[swift-evolution] Shorthand unwrap proposal

[James Campbell]

So if the function I run inside of the map has a return value of Void will
that still compile ?

*___________________________________*

*James⎥Head of Trolls*

*james at supmenow.com <james at supmenow.com>⎥supmenow.com <http://supmenow.com>*

*Sup*

*Runway East *

*10 Finsbury Square*

*London*

* EC2A 1AF *

On 23 June 2016 at 17:22, Jordan Rose <jordan_rose at apple.com> wrote:

> I think we’d still just recommend using ‘map’ for this. The reason
> Collection.map and Collection.forEach are different is because we don’t
> promise eager and in-order evaluation for Collection.map. But Optional only
> executes the closure one or zero times, so there’s no ambiguity.
>
> Jordan
>
>
> On Jun 23, 2016, at 09:15, James Campbell via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> So I have a real-life situation in an application, which does what you
> mention:
>
> This code is for a camera app, on a `didSet` it removes a device if set
> from the capture session, and if there is a new one set it adds it to the
> capture session.
>
> The add and remove methods indeed don't take optionals.
>
> So this is the code before:
>
> var audioDevice: AVCaptureDeviceInput? = nil {
>
>
>         willSet {
>
>             if let audioDevice = audioDevice {
>
>                captureSession?.removeInput(audioDevice)
>
>             }
>
>         }
>
>
>         didSet {
>
>             if audioDevice = audioDevice {
>
>                captureSession?.addInput(audioDevice)
>
>             }
>
>         }
>
>     }
>
>
> and after:
>
> var audioDevice: AVCaptureDeviceInput? = nil {
>
>
>         willSet {
>
>             audioDevice.unwrap {
>
>                 self.captureSession?.removeInput($0)
>
>             }
>
>         }
>
>
>         didSet {
>
>             audioDevice.unwrap {
>
>                 self.captureSession?.addInput($0)
>
>             }
>
>         }
>
>     }
>
>
> The last two saved me a lot of typing in these cases and I feel like it is
> more clear what is going on due to the `unwrap` method being clear in it's
> intent and the lack of `audioDevice` being repeated multiple times.
>
> *___________________________________*
>
> *James⎥Head of Trolls*
>
> *james at supmenow.com <james at supmenow.com>⎥supmenow.com
> <http://supmenow.com/>*
>
> *Sup*
>
> *Runway East *
>
> *10 Finsbury Square*
>
> *London*
>
> * EC2A 1AF *
>
> On 23 June 2016 at 17:11, Sean Heber <sean at fifthace.com> wrote:
>
>> I’m a bit tore on this myself. I see the appeal, but let’s say we had
>> such a function. If you wanted to use it with an named parameter it’d look
>> like this:
>>
>> myReallyLongOptionalName.unwrap { string in
>>   doSomethingWith(string)
>> }
>>
>> And that is actually *more* characters than the current approach:
>>
>> if let string = myReallyLongOptionalName {
>>   doSomethingWith(string)
>> }
>>
>> However it’d be a big win especially when you can skip $0 and the braces
>> entirely such as:
>>
>> myReallyLongOptionalName.unwrap(doSomethingWith)
>>
>> Of course if we were dealing with methods, you could write this like:
>>
>> myReallyLongOptionalName?.doSomething()
>>
>> And that is probably hard to beat.
>>
>> So I think the problem really only presents itself when you have an
>> optional that you need to unwrap and use as a parameter to something that
>> does not take an optional.
>>
>> I don’t have a solution - just trying to clarify the situation. :)
>>
>> l8r
>> Sean
>>
>>
>> > On Jun 23, 2016, at 10:36 AM, James Campbell via swift-evolution <
>> swift-evolution at swift.org> wrote:
>> >
>> > I was wondering if people would be open to adding an unwrap method to
>> the Optional type,  I already have a method like this which shortens code
>> for me.
>> >
>> > So this:
>> >
>> > let myReallyLongOptionalName: String? = "Hey"
>> >
>> > if let string = myReallyLongOptionalName {
>> >   doSomethingWith(string)
>> > }
>> >
>> > Could become"
>> >
>> > let myReallyLongOptionalName: String? = "Hey"
>> >
>> > myReallyLongOptionalName.unwrap {
>> >   doSomethingWith($0)
>> > }
>> >
>> > The block would only be fired if myReallyLongOptionalName has a value.
>> >
>> > ___________________________________
>> >
>> > James⎥Head of Trolls
>> >
>> > james at supmenow.com⎥supmenow.com
>> >
>> > Sup
>> >
>> > Runway East >
>> >
>> > 10 Finsbury Square
>> >
>> > London
>> >
>> > > EC2A 1AF
>> >
>> > _______________________________________________
>> > swift-evolution mailing list
>> > swift-evolution at swift.org
>> > https://lists.swift.org/mailman/listinfo/swift-evolution
>>
>>
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