[swift-evolution] [Review] SE-0122: Use colons for subscript declarations

[Jaden Geller]

> Python's __getitem__() method, C++'s [] operator are some analogous examples. Non -of them pretend not to be a function. The users of these features appear to be satisfied by the decision.

This seems irrelevant since Swift already has computed properties which pretend not to be a function.

> On Jul 20, 2016, at 7:13 PM, Duan via swift-evolution <swift-evolution at swift.org> wrote:
> 
> * What is your evaluation of the proposal <x-apple-data-detectors://3>?
> 
> -1. 
> 
> To me, subscripts have always seen more functions than properties for the fact that they can take arbitrary number of arguments. If we were to "clean up" its syntax, I'd rather align it with functions. Something along the lines of
> 
>   subscribe(get) func foo(_ x: X) -> Y
>   subscribe(set) func foo(_ y: Y)
> 
>  * Is the problem being addressed significant enough to warrant a change to Swift?
> 
> No. More importantly, the change is a regression visually.
> 
> * Does this proposal fit well with the feel and direction of Swift?
> 
> It's an attempt of a syntax dress-up.
> 
> * If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?
> 
> Python's __getitem__() method, C++'s [] operator are some analogous examples. Non -of them pretend not to be a function. The users of these features appear to be satisfied by the decision.
> 
>  * How much effort did you put into your review? A glance, a quick reading, or an in-depth study?
>  
> Quick read of proposal and discussion on ML.
> 
> Daniel Duan
> Sent from my iPhone
> 
> On Jul 20, 2016, at 10:17 AM, Jose Cheyo Jimenez via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> 
>> 
>>> On Jul 20, 2016, at 7:51 AM, Vladimir.S via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>> 
>>> +1 to clean up the syntax of subscripts. They acts as properties, not methods, so it is natural to express them with `:` and not with `->`.
>>> 
>>> Actually, I'd prefer additional change to use [] instead of () in declaration like:
>>> 
>>> subscript[externalName internalName: ParamType] : ElementType {
>>>    get { … }
>>>    set { … }
>>> }
>> 
>> I got to second this suggestion. To me this is an elegant solution. 
>> 
>> If subscripts are so special that Swift decided to give it its own name (as oppose to just making it two functions), 
>> why not declare it in a special way like the above?
>> 
>> I think that in addition to replacing -> with : if we replaced () with [] then it would be much clearer that this is not a function or property. 
>> 
>> subscript[externalName internalName: ParamType] : ElementType {
>>     get { … }
>>     set { … }
>> }
>> 
>> I don’t see another place in the language where [] would make more sense than here: 
>> Otherwise I don’t see  replacing -> with : as a big win like Dmitri Gribenko said down thread ->
>> 
>>>> I think by changing subscripts to use colons we would end in the opposite, but
>>>> totally symmetrical situation compared to what we have now.
>> 
>> 
>>  
>> 
>>> 
>>> especially if thinking about "Future directions" and confusion with parameterised accessor syntax(both declared with `()` but first used with `[]` and second with `()`).
>>> 
>>> On 20.07.2016 8:50, Chris Lattner via swift-evolution wrote:
>>>> Hello Swift community,
>>>> 
>>>> The review of "SE-0122: Use colons for subscript declarations " begins now and runs through July 24. The proposal is available here:
>>>> 
>>>> 	https://github.com/apple/swift-evolution/blob/master/proposals/0122-use-colons-for-subscript-type-declarations.md <https://github.com/apple/swift-evolution/blob/master/proposals/0122-use-colons-for-subscript-type-declarations.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 <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 contribute to 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 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 <https://github.com/apple/swift-evolution/blob/master/process.md>
>>>> 
>>>> Thank you,
>>>> 
>>>> -Chris Lattner
>>>> Review Manager
>>>> 
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>>>> 
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