[swift-evolution] [Discussion] Replacing Equal Signs with Colons For Attribute Arguments
Michael Wells
michael at michaelwells.com
Tue Feb 16 20:54:16 CST 2016
Aren’t we removing the use of snake case in Swift 3? So should @warn_unused_result be de-snake-cased?
> On Feb 16, 2016, at 6:45 PM, Ricardo Parada via swift-evolution <swift-evolution at swift.org> wrote:
>
> It looks very good.
>
> Thank you Erica.
>
>
>> On Feb 16, 2016, at 8:05 PM, Erica Sadun <erica at ericasadun.com <mailto:erica at ericasadun.com>> wrote:
>>
>> Adding:
>>
>> @available(*, unavailable, renamed: "MyRenamedProtocol")
>> typealias MyProtocol = MyRenamedProtocol
>>
>> @warn_unused_result(mutable_variant: "sortInPlace")
>> public func sort() -> [Self.Generator.Element]
>>
>> @available(*, deprecated, message: "it will be removed in Swift 3. Use the 'generate()' method on the collection.")
>> public init(_ bounds: Range<Element>)
>>
>> gist: https://gist.github.com/erica/d96011a5c22d9b995b91 <https://gist.github.com/erica/d96011a5c22d9b995b91>
>>
>> -- E
>>
>>> On Feb 16, 2016, at 5:43 PM, Charles Kissinger <crk at akkyra.com <mailto:crk at akkyra.com>> wrote:
>>>
>>>
>>>> On Feb 16, 2016, at 4:08 PM, Erica Sadun via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>
>>>> Ricardo,
>>>>
>>>> This proposal is so narrow that I believe *every single example possible* is already in there under motivation. Just sub out each "=" for ":" and you have the entire extent of the change.
>>>
>>> Hi Erica,
>>>
>>> I think Ricardo means full examples of the new style, including @ symbol, attribute-name, parens, attribute argument label and example attribute arguments. There are no full examples in the proposal of either the existing or proposed style.
>>>
>>> It might seem nit-picky (and it is :-)), but that’s the only way for us to evaluate how it will actually look in practice. (Yes, we could look up a few and type them in somewhere ourselves, but it would be nice to have them in the proposal.)
>>>
>>> —CK
>>>
>>>>
>>>> -- Erica
>>>>
>>>>> On Feb 16, 2016, at 5:03 PM, Ricardo Parada <rparada at mac.com <mailto:rparada at mac.com>> wrote:
>>>>>
>>>>> Hi Erica,
>>>>>
>>>>> I understand this is a draft and even though it may be obvious to many, I would add a few examples with the proposed solution.
>>>>>
>>>>> Thanks
>>>>> Ricardo Parada
>>>>>
>>>>>
>>>>>> On Feb 16, 2016, at 5:42 PM, Erica Sadun via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>>>
>>>>>> Thoughts and feedback appreciated. Thank you, -- Erica
>>>>>>
>>>>>>
>>>>>>
>>>>>> Replacing Equal Signs with Colons For Attribute Arguments
>>>>>>
>>>>>> Proposal: TBD
>>>>>> Author(s): Erica Sadun <http://github.com/erica>
>>>>>> Status: TBD
>>>>>> Review manager: TBD
>>>>>> <https://gist.github.com/erica/d96011a5c22d9b995b91#introduction>Introduction
>>>>>>
>>>>>> Attribute arguments are unlike other Swift language arguments. At the call site, they use = instead of colons to distinguish argument names from passed values. This proposal brings attributes into compliance with Swift standard practices by replacing the use of "=" with ":" in this one-off case.
>>>>>>
>>>>>> Discussion took place on the Swift Evolution mailing list in the [Discussion] Replacing Equal Signs with Colons For Attribute Arguments thread. Thanks to Doug Gregor <https://github.com/DougGregor> for suggesting this enhancement.
>>>>>>
>>>>>> <https://gist.github.com/erica/d96011a5c22d9b995b91#motivation>Motivation
>>>>>>
>>>>>> Attributes enable developers to annotate declarations and types with keywords that constrain behavior. Recognizable by their at-sign <http://foldoc.org/strudel> "@" prefix, attributes communicate features, characteristics, restrictions, and expectations of types and declarations to the Swift compiler. Common attributes include @noescape for parameters that cannot outlive the lifetime of a call, @convention, to indicates whether a type's calling conventions follows a Swift, C, or (Objective-C) block model, and @available to enumerate a declaration's compatibility with platform and OS versions. Swift currently offers about a dozen distinct attributes, and is likely to expand this vocabulary in future language updates.
>>>>>>
>>>>>> Some attributes accept arguments: @attribute-name(attribute-arguments) including @available and @warn_unused_result. In the current grammar, an equal sign separates attribute argument keywords from values:
>>>>>>
>>>>>> introduced=version-number
>>>>>> deprecated=version-number
>>>>>> obsoleted=version-number
>>>>>> message=message
>>>>>> renamed=new-name
>>>>>> mutable_variant=method-name
>>>>>> Using = is out of step with other Swift parameterization call-site patterns. Tweaking the grammar to match the rest of Swift introduces a small change that adds consistency across the language.
>>>>>>
>>>>>> parameter name: parameter value
>>>>>> <https://gist.github.com/erica/d96011a5c22d9b995b91#detail-design>Detail Design
>>>>>>
>>>>>> This proposal replaces the use of = with : in the balanced tokens used to compose an attribute argument clause along the following lines:
>>>>>>
>>>>>> attribute → @ attribute-name attribute-argument-clause<sub>opt</sub>
>>>>>> attribute-name → identifier
>>>>>> attribute-argument-clause → ( balanced-tokens<sub>opt<opt> )
>>>>>> balanced-tokens → balanced-token
>>>>>> balanced-tokens → balanced-token, balanced-tokens
>>>>>> balanced-token → attribute-argument-label : attribute argument-value
>>>>>> This design can be summarized as "wherever current Swift attributes use =, use : instead".
>>>>>>
>>>>>> <https://gist.github.com/erica/d96011a5c22d9b995b91#alternatives-considered>Alternatives Considered
>>>>>>
>>>>>> There are no alternatives to put forth other than not accepting this proposal.
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>>>>>
>>>>
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>>
>
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