Eliminating optional protocol requirements is fine by me. The proposal mentions 
‘correcting’ the optional protocol requirement pattern by changing the methods 
to optional closure properties, but my feeling is that this ‘solution’ just 
acts to continue and perhaps encourage the anti-pattern established by ObjC. I 
think a native Swift design would be much better off using optional closure 
properties on the table view itself.

A common theme in these ObjC optional protocol requirements is the first 
parameter being an instance whichever class ‘requires’ the method. Yet on the 
rare occasion of the instance potentially having more than one value, the 
implementation for each instance is often so different that my first action 
will be to add a switch between the possible instances (which, of course, means 
having those components available as IBOutlet properties anyway).

I suggest a much better solution to optional protocol requirements in Swift is 
the creation of wrappers for UIKit components. These would implement the 
protocol requirements, and expose optional closure properties for their their 
public API. Making them properties makes it far clearer that the behaviour of 
the container will change if a value is provided, and would remove the 
persistent need to apply @objc to any Swift types dealing with UIKit. I 
understand this would be a manual task, but I just don't think there is a good 
automatic solution to this problem.

------------ Begin Message ------------ 
Group: gmane.comp.lang.swift.evolution 
MsgID: <[email protected]> 

Hello Swift community,

The review of "SE-0070: Make Optional Requirements Objective-C only" begins now 
and runs through May 2. The proposal is available here:

https://github.com/apple/swift-evolution/blob/master/proposals/0070-optional-requirements.md

Reviews are an important part of the Swift evolution process. All reviews 
should be sent to the swift-evolution mailing list at

https://lists.swift.org/mailman/listinfo/swift-evolution

or, if you would like to keep your feedback private, directly to the review 
manager.

What goes into a review?

The goal of the review process is to improve the proposal under review through 
constructive criticism and, eventually, determine the direction of Swift. When 
writing your review, here are some questions you might want to answer in your 
review:

* What is your evaluation of the proposal?
* Is the problem being addressed significant enough to warrant a change to 
Swift?
* Does this proposal fit well with the feel and direction of Swift?
* If you have you used other languages or libraries with a similar feature, how 
do you feel that this proposal compares to those?
* How much effort did you put into your review? A glance, a quick reading, or 
an in-depth study?

More information about the Swift evolution process is available at

https://github.com/apple/swift-evolution/blob/master/process.md

Thank you,

-Chris Lattner
Review Manager
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From James F


From James F
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