[swift-evolution] Closure delegation

[James Campbell]

On Fri, Dec 11, 2015 at 12:14 PM, James Campbell <james at supmenow.com> wrote:

> So I don't like this way of declaring it as it is not very clear what it
> is doing  but I actually prefer the javascript way of binding, so in your
> example the code would be this:
>
> func prepareSomething(setup:() -> ()) {
>     let bar = BarImplementation()
>     // code before
>     setup().bind(bar)
>     // code after
> }
>
> The bind method lets Swift know it should bind this to `bar`, so now this
> is the same as writing `bar`. So in your example:
>
> without delegation
> prepareSomething { delegate in
>     delegate.someConfig = "Hello World"
> }
>
> with binding
> prepareSomething {
>     someConfig = "Hello World"
> }
>
> These would work the same :)
>
> On Fri, Dec 11, 2015 at 11:49 AM, Pierre Monod-Broca <
> pierremonodbroca at gmail.com> wrote:
>
>> without delegation
>> prepareSomething { delegate in
>>     delegate.someConfig = "Hello World"
>> }
>>
>> with delegation
>> prepareSomething {
>>     someConfig = "Hello World"
>> }
>>
>> The exemple is not very compelling, but in a manifest file it would
>> reduce boiler plate.
>>
>> Pierre
>>
>> Le 11 déc. 2015 à 12:29, James Campbell <james at supmenow.com> a écrit :
>>
>> Whats the advantage over this ?
>>
>> protocol Bar {
>>>     var someConfig: String { get set }
>>> }
>>>
>>> func prepareSomething(setup: (delegate: Bar) -> ()) {
>>>
>>
>> On Fri, Dec 11, 2015 at 11:27 AM, Pierre Monod-Broca <
>> pierremonodbroca at gmail.com> wrote:
>>
>>>
>>> Le 11 déc. 2015 à 11:54, James Campbell <james at supmenow.com> a écrit :
>>>
>>> Could you explain a little more its a bit confusing ?
>>>
>>> On Fri, Dec 11, 2015 at 10:32 AM, Pierre Monod-Broca via swift-evolution
>>> <swift-evolution at swift.org> wrote:
>>>
>>>> A groovy closure can have a delegate which replaces `this` as the
>>>> default receiver. The issue in groovy is that it is not compatible with
>>>> static compilation, and there is no way to know from the code what is the
>>>> type of the delegate.
>>>>
>>>> It works great for DSL. It would work great the Swift Package Manager
>>>> manifest, among other things.
>>>>
>>>> It could look like this in swift
>>>>
>>>> protocol Bar {
>>>>     var someConfig: String { get set }
>>>> }
>>>>
>>>> func prepareSomething(setup: @delegate Bar -> () -> ()) {
>>>>
>>> Here we define a function `prepareSomething(_:)` which receives one
>>> parameter: a closure that takes a delegate conforming to `Bar`, and
>>> otherwise take no parameter and returns nothing
>>>
>>>     let bar = BarImplementation()
>>>>     // code before
>>>>     setup(bar)()
>>>>
>>> Here we pass a delegate to the closure, then call the closure
>>>
>>>     // code after
>>>> }
>>>>
>>>> prepareSomething { () -> () in
>>>>
>>> Here we call the function `prepareSomething(_:)` with a closure which we
>>> define a the same time
>>>
>>>     someConfig = "Hello world"
>>>>
>>> Here `someConfig` is a property of the closure’s delegate
>>>
>>> }
>>>>
>>>> Where `someConfig` would refer to bar.
>>>>
>>>>
>>> I’m not sure about the syntax, we could also declare the delegate that
>>> way, maybe :
>>> func prepareSomething(doSomething: @delegate(Bar) () -> ()) {
>>>     /**/
>>> }
>>>
>>> Pierre
>>>>
>>>>
>>>> _______________________________________________
>>>> swift-evolution mailing list
>>>> swift-evolution at swift.org
>>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>>>
>>>>
>>>
>>>
>>> --
>>>  Wizard
>>> james at supmenow.com
>>> +44 7523 279 698
>>>
>>>
>>>
>>>
>>
>>
>> --
>>  Wizard
>> james at supmenow.com
>> +44 7523 279 698
>>
>>
>>
>
>
> --
>  Wizard
> james at supmenow.com
> +44 7523 279 698
>



-- 
 Wizard
james at supmenow.com
+44 7523 279 698
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