[swift-users] Calling default implementation of protocol methods as selectors

[Geordie Jay]

Thanks for the amendment, and sorry for the (lack of) formatting. I
painstakingly typed that on my phone with manually-spaced indenting, which
the Inbox app unhelpfully removed entirely when I pressed send. Pasting
into Xcode should do the trick though..

Geordie
On Sun 4. Jun 2017 at 14:49, Zhao Xin <owenzx at gmail.com> wrote:

> You should change to another way. Using `self` in `super.init` is not
> allowed.
>
> Zhaoxin
>
> On Sun, Jun 4, 2017 at 12:38 PM, Geordie Jay <geojay at gmail.com> wrote:
>
>> I am dealing with a variant of this on Android right now. I have just
>> subclassed e.g. UITapGestureRecognizer to perform the 2nd variant above and
>> externally accept a closure as its argument. I'm writing this on my phone
>> so forgive any syntax errors or accidental omissions:
>>
>> class TapGestureRecognizer: UITapGestureRecognizer {
>> var onTap: (() -> Void)?
>> init(onTap: (() -> Void)?) {
>> self.onTap = onTap
>> super.init(target: self, action: #selector(internalTapHandler))
>> }
>>
>> @objc private func internalTapHandler() {
>> onTap?()
>> }
>> }
>>
>> class Baz: Foo {
>> init() {
>> let tapRecognizer = TapGestureRecognizer(onTap: self.bar)
>> }
>> }
>>
>>
>> Cheers,
>> Geordie
>>
>> On Sat 3. Jun 2017 at 16:53, Nate Birkholz via swift-users <
>> swift-users at swift.org> wrote:
>>
>>> Thanks, the second had occurred to me, but felt a little too much like
>>> in practice it would make the code harder to understand.
>>>
>>> On Fri, Jun 2, 2017 at 9:58 PM, Zhao Xin <owenzx at gmail.com> wrote:
>>>
>>>> I found two workarounds.
>>>>
>>>> 1.
>>>>
>>>> protocol Foo: class {
>>>>
>>>>     func bar()
>>>>
>>>> }
>>>>
>>>>
>>>> class Base:Foo {
>>>>
>>>>     @objc func bar() {
>>>>
>>>>         print("bar")
>>>>
>>>>     }
>>>>
>>>> }
>>>>
>>>>
>>>> class Baz: Base {
>>>>
>>>>     override init() {
>>>>
>>>>         super.init()
>>>>
>>>>         let tapRecognizer = UITapGestureRecognizer(target: self,
>>>> action: #selector(bar))
>>>>
>>>>     }
>>>>
>>>> }
>>>>
>>>> 2.
>>>>
>>>> protocol Foo: class {
>>>>
>>>>     func bar()
>>>>
>>>> }
>>>>
>>>>
>>>> extension Foo {
>>>>
>>>>     func bar() {
>>>>
>>>>         print("bar")
>>>>
>>>>     }
>>>>
>>>> }
>>>>
>>>>
>>>> class Baz: Foo {
>>>>
>>>>     init() {
>>>>
>>>>         let tapRecognizer = UITapGestureRecognizer(target: self,
>>>> action: #selector(delegate))
>>>>
>>>>     }
>>>>
>>>>
>>>>
>>>>     @objc func delegate() {
>>>>
>>>>         bar()
>>>>
>>>>     }
>>>>
>>>> }
>>>>
>>>>
>>>> Zhao Xin
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Sat, Jun 3, 2017 at 10:35 AM, Nate Birkholz via swift-users <
>>>> swift-users at swift.org> wrote:
>>>>
>>>>> protocol Foo: class {
>>>>>     func bar()
>>>>> }
>>>>>
>>>>> extension Foo {
>>>>>     func bar() {
>>>>>          print("bar")
>>>>>     }
>>>>> }
>>>>>
>>>>> class Baz: Foo {
>>>>>     init() {
>>>>>         let tapRecognizer = UITapGestureRecognizer(target: self,
>>>>> action: #selector(bar))
>>>>>     }
>>>>> }
>>>>>
>>>>> the #selector tells me: "Argument of '#selector' refers to instance
>>>>> method 'bar()' that is not exposed to Objective-C" and asks me to add @objc
>>>>> to the method definition.
>>>>>
>>>>> Adding @objc to the method tells me: "@objc can only be used with
>>>>> members of classes, @objc protocols, and concrete extensions of classes"
>>>>>
>>>>> Adding @objc to the protocol doesn't fix it, just introduces new
>>>>> issues.
>>>>>
>>>>> "dynamic" cannot be applied to a protocol, so cannot be used
>>>>> alternatively.
>>>>>
>>>>> Is there a way to get around this? If a method is called by a gesture
>>>>> recognizer, is there no way to have a default protocol implementation? I'd
>>>>> like to use default implementations if possible to make my code more DRY.
>>>>>
>>>>> Is there a roadmap/plan for swift-native selector dispatch?
>>>>>
>>>>> Thanks. I look forward to the inevitable reply revealing the dumb
>>>>> thing I missed. :)
>>>>>
>>>>> --
>>>>> Nate Birkholz
>>>>>
>>>>> _______________________________________________
>>>>> swift-users mailing list
>>>>> swift-users at swift.org
>>>>> https://lists.swift.org/mailman/listinfo/swift-users
>>>>>
>>>>>
>>>>
>>>
>>>
>>> --
>>> Nate Birkholz
>>> _______________________________________________
>>> swift-users mailing list
>>> swift-users at swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-users
>>>
>>
>
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