[swift-evolution] [swift-evolution-announce] [Review] SE-0026 Abstract classes and methods

[David Owens II]

Building the functionality into abstract classes artificially limits the context for the problem though.

For example, there are cases where it's desirable for a protocol to be able to specify the storage mechanism for a property. If a protocol gains the ability to do that, that's just one benefit that abstract classes provide that is no longer necessary.

-David

> On Feb 28, 2016, at 9:28 AM, Goffredo Marocchi via swift-evolution <swift-evolution at swift.org> wrote:
> 
> So far while pushing for protocol oriented programming as one of Swift's distinctive features, the Swift team (or at least Chris Lattner) stated that inheritance is not a patter which is bad per se, it is a pattern which has its uses and it is fully supported by Swift just as much as other patterns Swift makes available. In my opinion of you have a feature, this feature should not fight with a hand tied behind its back: the "if you do it, do it well" approach :).
> 
> Answers like this seem to be the next best thing from asking to remove inheritance outright or to limit it more. Improving protocols, improving functional programming support, etc... all of that is orthogonal to improving OOP through class inheritance. 
> Support for abstract classes does not force people to use inheritance. Instead of doc using energies pushing down proposals that advocate for improving class based inheritance, I see energy better spent in making proposals that improve protocols unless they get filled by inheritance die hard afraid of the success of protocols meaning a death sentence for inheritance :).
> 
> Sent from my iPhone
> 
> On 28 Feb 2016, at 17:11, Trent Nadeau via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> 
>> >       • What is your evaluation of the proposal?
>> -1. I would prefer something like mixins that could work without inheritance and would thus also work with value types.
>> 
>> >       • Is the problem being addressed significant enough to warrant a change to Swift?
>> Yes, although I don't think abstract classes that force inheritance and only work for classes is the answer.
>> 
>> >       • Does this proposal fit well with the feel and direction of Swift?
>> No.
>> 
>> >       • If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?
>> My opinion is based on other languages I've used that have better ways to handle this (Ruby, Python, D) as well as the downsides I've seen with abstract classes in Java and C++.
>> 
>> >       • How much effort did you put into your review? A glance, a quick reading, or an in-depth study?
>> I've followed the various threads on this topic that have come up since Swift was open-sourced.
>> 
>> On Sun, Feb 28, 2016 at 12:02 PM, Антон Жилин <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> My GMail keeps breaking threads. I wrote this in reply to this post of Matthew Johnson:
>> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160222/011351.html <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160222/011351.html>
>> 
>> 2016-02-28 19:50 GMT+03:00 Антон Жилин <antonyzhilin at gmail.com <mailto:antonyzhilin at gmail.com>>:
>> It would be interesting to know your opinion on "mixins" proposal. Do you need some kind of "abstract classes for structs", perhaps with multiple inheritance, or you find that more elegant architectual solutions to problems can be found, without partially implemented constructs?
>> https://gist.github.com/Anton3/f0550922c1be0fc5447c <https://gist.github.com/Anton3/f0550922c1be0fc5447c>
>> 
>> 
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>> 
>> 
>> 
>> -- 
>> Trent Nadeau
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