[swift-users] Attempting to call default protocol implementation crashes Playground

[Игорь Никитин]

And, as I know, it's not possible to call protocol's implementation in that case


> 16 нояб. 2016 г., в 9:09, Игорь Никитин via swift-users <swift-users at swift.org> написал(а):
> 
> Right, it’s a recursion, because this 
> 
> (self as FooPro).fooFunc()
> 
> Will call FooClass’s  method implementation
> 
> You can read more about dispatch rules here: https://medium.com/ios-os-x-development/swift-protocol-extension-method-dispatch-6a6bf270ba94#.hkh1rc56p
> 
> 
> 
>> 16 нояб. 2016 г., в 4:29, Rick Mann via swift-users <swift-users at swift.org> написал(а):
>> 
>> Okay. I coudln't find official documentation on this, and I don't currently need to do this, but wanted to fully understand it.
>> 
>>> On Nov 15, 2016, at 17:27 , zh ao <owenzx at gmail.com> wrote:
>>> 
>>> 'Default' implementation in protocol extension is used as fail safe. You should not consider it like something super class does. If you want it that way, use class inheritance instead.
>>> 
>>> Zhaoxin
>>> 
>>> Get Outlook for iOS
>>> 
>>> _____________________________
>>> From: Rick Mann via swift-users <swift-users at swift.org>
>>> Sent: 星期三, 十一月 16, 2016 07:51
>>> Subject: Re: [swift-users] Attempting to call default protocol implementation crashes Playground
>>> To: Dan Loewenherz <dan at lionheartsw.com>
>>> Cc: swift-users <swift-users at swift.org>
>>> 
>>> 
>>> Well, this is a standard protocol default implementation. I was experimenting to see if it was possible to call the default implementation after providing a concrete implementation.
>>> 
>>>> On Nov 15, 2016, at 14:47 , Dan Loewenherz <dan at lionheartsw.com> wrote:
>>>> 
>>>> What are you trying to accomplish here, more concretely?
>>>> 
>>>> My first thought is that you shouldn't implement the same function in both a protocol extension and a conforming class. Why not just give them different names and call the function from within the extension instead of from the class? E.g.
>>>> 
>>>> protocol FooPro {
>>>> func _fooFunc()
>>>> }
>>>> 
>>>> extension FooPro {
>>>> func fooFunc() {
>>>> print("fooFunc default")
>>>> _fooFunc()
>>>> }
>>>> }
>>>> 
>>>> class FooClass: FooPro {
>>>> func _fooFunc() {
>>>> print("fooFunc FooClass")
>>>> }
>>>> }
>>>> 
>>>> let fc = FooClass()
>>>> fc.fooFunc()
>>>> 
>>>> Dan
>>>> 
>>>> On Tue, Nov 15, 2016 at 4:28 PM, Rick Mann via swift-users <swift-users at swift.org> wrote:
>>>> The following gives Xcode 8.1 a very hard time. Eventually I get a Bad Access on the last line. I'm guessing it's a recursive call. Is there any way to call the default implementation from a "real" implementation?
>>>> 
>>>> protocol FooPro
>>>> {
>>>> func fooFunc()
>>>> }
>>>> 
>>>> extension FooPro
>>>> {
>>>> func
>>>> fooFunc()
>>>> {
>>>> print("fooFunc default")
>>>> }
>>>> }
>>>> 
>>>> class FooClass : FooPro
>>>> {
>>>> func
>>>> fooFunc()
>>>> {
>>>> (self as FooPro).fooFunc()
>>>> print("fooFunc FooClass")
>>>> }
>>>> }
>>>> 
>>>> let fc: FooPro = FooClass()
>>>> fc.fooFunc()
>>>> 
>>>> 
>>>> Thanks!
>>>> 
>>>> 
>>>> --
>>>> Rick Mann
>>>> rmann at latencyzero.com
>>>> 
>>>> 
>>>> _______________________________________________
>>>> swift-users mailing list
>>>> swift-users at swift.org
>>>> https://lists.swift.org/mailman/listinfo/swift-users
>>>> 
>>> 
>>> 
>>> -- 
>>> Rick Mann
>>> rmann at latencyzero.com
>>> 
>>> 
>>> _______________________________________________
>>> swift-users mailing list
>>> swift-users at swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-users
>>> 
>>> 
>> 
>> 
>> -- 
>> Rick Mann
>> rmann at latencyzero.com
>> 
>> 
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>> swift-users at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-users
> 
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