[swift-evolution] [Late Pitch] Deprecations, Moves, and Renames

Thu Sep 8 18:35:57 CDT 2016

On Sep 7, 2016, at 12:58 PM, Tim Vermeulen via swift-evolution <swift-evolution at swift.org> wrote:
> They’re still in Swift 3. Did something go wrong, or will they simply not show up in the final Swift 3.0?

Please elaborate on what you mean: what is in that shouldn’t be?

-Chris

> 
>> On 10 Aug 2016, at 22:28, Dave Abrahams <dabrahams at apple.com <mailto:dabrahams at apple.com>> wrote:
>> 
>> 
>> on Wed Aug 10 2016, Tim Vermeulen <tvermeulen-AT-me.com <http://tvermeulen-at-me.com/>> wrote:
>> 
>>> Some protocols of SE-0104 seem to be part of the latest Swift 3
>>> snapshots (Arithmetic, FixedWidthInteger, etc) - was this a mistake
>>> then, if they won’t be in Swift 3.0?
>> 
>> Yes, they've been pulled out of the release branch:
>> https://github.com/apple/swift/pull/4112#issuecomment-238451509 <https://github.com/apple/swift/pull/4112#issuecomment-238451509>
>> 
>>> 
>>> 
>>>> on Wed Aug 10 2016, Ben Rimmington<me-AT-benrimmington.com <http://me-at-benrimmington.com/>>wrote:
>>>> 
>>>>>> On 10 Aug 2016, at 00:36, Dave Abrahams wrote:
>>>>>> 
>>>>>>> on Tue Aug 09 2016, Ben Rimmington wrote:
>>>>>>> 
>>>>>>>> On 9 Aug 2016, at 20:09, Dave Abrahams wrote:
>>>>> 
>>>>>>>> 
>>>>>>>> Hi Everybody,
>>>>>>>> 
>>>>>>>> With another round of apologies for taking late action, we propose to
>>>>>>>> make some deprecations, moves, and renames. The background for these
>>>>>>>> moves is as follows:
>>>>>>>> 
>>>>>>>> We've always known that when Swift reached ABI stability
>>>>>>>> (now slated for
>>>>>>>> Swift 4), we would be committed to supporting many of the standard
>>>>>>>> library's design decisions for years to come. What we only realized
>>>>>>>> very recently is that, although Swift 3.0 is *not* shipping with a
>>>>>>>> stable ABI, the promise that Swift 3.0 code will work with Swift 4.0
>>>>>>>> code creates similar implications when it comes to certain protocols,
>>>>>>>> today. Especially where these protocols show up in refinement
>>>>>>>> hierarchies, we can't keep Swift 3 code working in the future without
>>>>>>>> carrying them forward into future libraries.
>>>>>>>> 
>>>>>>>> The proposed changes are as follows:
>>>>>>>> 
>>>>>>>> * Move `CustomPlaygroundQuickLookable` to the
>>>>>>>> PlaygroundSupport module.
>>>>>>>> This component is really only useful for playgrounds, and doesn't
>>>>>>>> belong in the standard library.
>>>>>>> 
>>>>>>> I didn't think it was possible to `import PlaygroundSupport` unless the
>>>>>>> current file is within a playground. If so, how can corelibs-foundation
>>>>>>> or third-party modules add `CustomPlaygroundQuickLookable`
>>>>>>> conformance?
>>>>>> 
>>>>>> Ahhh... yeah, I didn't realize that, and we don't have time to change
>>>>>> that restriction for Swift 3. It's not a problem for
>>>>>> corelibs-foundation but it would be for 3rd-party libraries.
>>>>>> 
>>>>>> OK, Dmitri and I just figured out how we can change the home of these
>>>>>> types for Swift 4 without breaking Swift 3 code (mirrors to the rescue!)
>>>>>> So I'm going to withdraw this part of the proposal.
>>>>> 
>>>>> Will the following need to be reverted?
>>>>> 
>>>>> <https://github.com/apple/swift/pull/4089 <https://github.com/apple/swift/pull/4089>>
>>>>> 
>>>>> <https://github.com/apple/swift-xcode-playground-support/commit/aab7af4 <https://github.com/apple/swift-xcode-playground-support/commit/aab7af4>>
>>>>> <https://github.com/apple/swift-xcode-playground-support/commit/865fd0c <https://github.com/apple/swift-xcode-playground-support/commit/865fd0c>>
>>>>> <https://github.com/apple/swift-xcode-playground-support/commit/ab605ef <https://github.com/apple/swift-xcode-playground-support/commit/ab605ef>>
>>>>> <https://github.com/apple/swift-xcode-playground-support/commit/4bd6575 <https://github.com/apple/swift-xcode-playground-support/commit/4bd6575>>
>>>>> <https://github.com/apple/swift-xcode-playground-support/commit/acee2e1 <https://github.com/apple/swift-xcode-playground-support/commit/acee2e1>>
>>>> Technically, no, because typealiases make it unnecessary, but yes, we
>>>> plan to do that.
>>>> 
>>>>>>>> * Deprecate the Indexable protocols with a message
>>>>>>>> indicating that they
>>>>>>>> will be gone in Swift 4. These protocols are implementation details
>>>>>>>> of the standard library designed to work around language limitations
>>>>>>>> that we expect to be gone in Swift 4. There's no reason for anyone to
>>>>>>>> ever touch these; users should always use a corresponding Collection
>>>>>>>> protocol (e.g. instead of MutableIndexable, use MutableCollection).
>>>>>>>> 
>>>>>>>> * Deprecate the ExpressibleByStringInterpolation protocol with a
>>>>>>>> message indicating that its design is expected to change. We know
>>>>>>>> this protocol to be mis-designed
>>>>>>>> (https://bugs.swift.org/browse/SR-1260 <https://bugs.swift.org/browse/SR-1260>) and limited
>>>>>>>> (https://bugs.swift.org/browse/SR-2303 <https://bugs.swift.org/browse/SR-2303>), but there's no time
>>>>>>>> to fix it
>>>>>>>> for Swift 3. If we knew what the new design should look like, we
>>>>>>>> might be able to calculate that the current API is supportable in a
>>>>>>>> forward-compatible way (as we do for Comparable). Unfortunately, we
>>>>>>>> do not.
>>>>>>>> 
>>>>>>>> * Rename Streamable to TextOutputStreamable and add a deprecated
>>>>>>>> Streamable typealias for it. Now that OutputStream been renamed to
>>>>>>>> TextOutputStream, we should also move Streamable out of the way.
>>>>> 
>>>>> In apple/swift#4131, these lines have overrun the 80 column limit:
>>>>> 
>>>>> <https://github.com/apple/swift/blob/f2443f4/stdlib/public/core/Mirror.swift#L843 <https://github.com/apple/swift/blob/f2443f4/stdlib/public/core/Mirror.swift#L843>>
>>>>> <https://github.com/apple/swift/blob/f2443f4/stdlib/public/core/Mirror.swift#L893 <https://github.com/apple/swift/blob/f2443f4/stdlib/public/core/Mirror.swift#L893>>
>>>>> 
>>>>> <https://github.com/apple/swift/blob/f2443f4/stdlib/public/core/Print.swift#L177 <https://github.com/apple/swift/blob/f2443f4/stdlib/public/core/Print.swift#L177>>
>>>>> <https://github.com/apple/swift/blob/f2443f4/stdlib/public/core/Print.swift#L228 <https://github.com/apple/swift/blob/f2443f4/stdlib/public/core/Print.swift#L228>>
>>>>> 
>>>>> TextFormatting.rst also needs `Streamable` =>`TextOutputStreamable`:
>>>>> 
>>>>> <https://github.com/apple/swift/blob/master/docs/TextFormatting.rst <https://github.com/apple/swift/blob/master/docs/TextFormatting.rst>>
>>>> Pull requests gratefully accepted for all of these corrections
>>>> 
>>>>>>>> Deprecation is being proposed instead of underscoring or renaming
>>>>>>>> because it allows existing code to keep working (with warnings). At
>>>>>>>> this late stage, it would be bad to actually break anything.
>>>>>>> 
>>>>>>> If the SE-0104 (protocol-oriented integers) proposal has been deferred,
>>>>>>> should any protocols (e.g. SignedNumber) be deprecated?
>>>>> 
>>>>> Will the SE-0104 proposal be accepted for Swift 4.0?
>>>> It is expected to be. We may even be able to get it into a Swift 3
>>>> point-release (e.g. 3.1)
>>>> 
>>>> --
>>>> Dave
>>>> 
>>>> 
>>>> 
>> 
>> -- 
>> -Dave
> 
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