[swift-evolution] [Review] SE-0018 Flexible Memberwise Initialization

[Félix Cloutier]

Meta: most reviews have the review dates in the Status field of their document, this one doesn't. I was a little confused at first.

For the proposal itself:

# What is your evaluation of the proposal?

+1

# Is the problem being addressed significant enough to warrant a change to Swift?

Yes, I write a lot of code just to initialize code. This will probably make some of that code clearer.

# Does this proposal fit well with the feel and direction of Swift?

Probably?

# If you have you used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?

I frequently write C++ and Python and neither of them have it. This is especially annoying for short programs.

# C# has an initializer syntax that allows you to assign properties at creation time, and it is handy:

> Foo foo = new Foo() {
> 	Bar = "bar",
> 	Baz = 1,
> };

However, this pattern wouldn't be of much help in Swift, where most types don't have a reasonable default value.

# How much effort did you put into your review? A glance, a quick reading, or an in-depth study?

I followed the first week and a half of the proposal.

With all this said, I am confused with the way the proposal is written. The Proposed Solution section talks about opt-in memberwise initialization with the memberwise modifier on properties, but it is listed as a future direction and the Detailed Design makes no mention of it. I would like to be clear that my current appreciation of the proposal only extends to the Detailed Design, and not necessarily to the future directions.

Félix

> Le 6 janv. 2016 à 19:04:41, Dave Abrahams via swift-evolution <swift-evolution at swift.org> a écrit :
> 
>> 
>> On Jan 6, 2016, at 2:47 PM, Chris Lattner via swift-evolution <swift-evolution at swift.org> wrote:
>> 
>> Hello Swift community,
>> 
>> The review of "Flexible Memberwise Initialization" begins now and runs through January 10th. The proposal is available here:
>> 
>> 	https://github.com/apple/swift-evolution/blob/master/proposals/0018-flexible-memberwise-initialization.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?
> 
> It’s okay.
> 
>> 	* Is the problem being addressed significant enough to warrant a change to Swift?
> 
> I’m lukewarm about that.  I have never found writing out the initializers I want to be a significant burden, and I find my code is better when they’re explicit.  Every new feature increases the language's complexity and surface area, and I fear this one is not going to pay its way.
> 
>> 	* Does this proposal fit well with the feel and direction of Swift?
> 
> Yes, but I worry that it may be too early to add it.  Other features in this space, like truly generic variadics, may well obsolete anything we do today.  I’m not sure we should be designing convenience features that are likely to overlap with more general features coming down the road unless the inconvenience is very painful… which I personally don’t find it to be.
> 
>> 	* If you have you used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?
> 
> The proposal is more elegant than how you’d do this in Python, but on the other hand the mechanisms you’d use in Python are not single-purpose language features directed at memberwise initialization; they definitely pay their way because they can be used for much more.
> 
>> 	* How much effort did you put into your review? A glance, a quick reading, or an in-depth study?
> 
> A glance, admittedly.
> 
>> More information about the Swift evolution process is available at
>> 
>> 	https://github.com/apple/swift-evolution/blob/master/process.md
>> 
>> Thank you,
>> 
>> -Chris
>> Review Manager
>> _______________________________________________
>> swift-evolution mailing list
>> swift-evolution at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
> 
> -Dave
> 
> 
> 
> _______________________________________________
> swift-evolution mailing list
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> https://lists.swift.org/mailman/listinfo/swift-evolution

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