None of those are affected. See the note in the proposal. ~Robert Widmann
> On May 5, 2017, at 1:16 AM, Adrian Zubarev <adrian.zuba...@devandartist.com> > wrote: > > Hi Robert, > > I’m trying to understand the impact of your proposal and the feature you want > to remove from the language. Could you describe a little more on how if ever > this affects tuple destructuring? > > var (a, b, c) = (0, "", 0) > > (a, b) = (42, "Hello Swift") > > (a = 42, b = "Hello Swift") > > var (x, y) = (0, 42) > > (x, y) = (y, x) // swap without a temporary value > > > > -- > Adrian Zubarev > Sent with Airmail > > Am 5. Mai 2017 um 04:15:12, Robert Widmann via swift-evolution > (swift-evolution@swift.org <mailto:swift-evolution@swift.org>) schrieb: > >> Hi all, >> >> So sorry that this proposal comes so late in the game, but I feel it’s too >> important not to bring it to the attention of the community now. Attached >> is a proposal to deprecate a language feature many of you will probably have >> never had the chance to use: Tuple Shuffles. I’ve attached a copy of the >> first draft of the proposal below, but the latest copy can be read on Github >> <https://github.com/apple/swift-evolution/pull/705/files>. >> >> Thanks! >> >> ~Robert Widmann >> >> Deprecate Tuple Shuffles >> Proposal: SE-NNNN >> <https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-filename.md> >> Authors: Robert Widmann <https://github.com/codafi> >> Review Manager: TBD >> Status: Awaiting review >> >> <https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#introduction>Introduction >> >> This proposal seeks the deprecation of a little-known feature of Swift >> called a "Tuple Shuffle". >> >> >> <https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#motivation>Motivation >> >> A tuple-shuffle is an undocumented feature of Swift in which one can >> re-order the indices of a tuple by writing a pattern that describes a >> permutation in a syntax reminiscent of adding type-annotations to a >> parameter list: >> >> let a = (x: 1, y: 2) >> var b: (y: Int, x: Int) >> b = a >> It can be used to simultaneously destructure and reorder a tuple: >> >> let tuple = (first: 0, second: (x: 1, y: 2)) >> let (second: (x: b, y: c), first: a) = tuple >> It can also be used to map parameter labels out of order in a call >> expression: >> >> func foo(_ : (x : Int, y : Int)) {} >> foo((y: 5, x: 10)) // Valid >> Note that a tuple shuffle is distinct from a re-assignment through a tuple >> pattern. For example, this series of statements will continue to function as >> before: >> >> var x = 5 >> var y = 10 >> var z = 15 >> (z, y, x) = (x, z, y) >> Their inclusion in the language complicates every part of the compiler >> stack, uses a syntax that can be confused for type annotations >> <https://twitter.com/CodaFi_/status/860246169854894081>, contradicts the >> goals of earlier SE's (see SE-0060 >> <https://github.com/apple/swift-evolution/blob/9cf2685293108ea3efcbebb7ee6a8618b83d4a90/proposals/0060-defaulted-parameter-order.md>), >> and makes non-sensical patterns possible in surprising places. >> >> Take switch-statements, for example: >> >> switch ((0, 0), 0){ >> case (_ : let (y, z), _ : let s): () // We are forbidden from giving these >> patterns names other than "_" >> default: () >> } >> This proposal seeks to deprecate them in Swift 3 compatibility mode and >> enforce that deprecation as a hard error in Swift 4 to facilitate their >> eventual removal from the language. >> >> >> <https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#proposed-solution>Proposed >> solution >> >> Construction of Tuple Shuffle Expressions will become a warning in Swift 3 >> compatibility mode and will be a hard-error in Swift 4. >> >> >> <https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#detailed-design>Detailed >> design >> >> In addition to the necessary diagnostics, the grammar will be ammended to >> simplify the following productions: >> >> tuple-pattern → (tuple-pattern-element-list <opt>) >> tuple-pattern-element-list → tuple-pattern-element | tuple-pattern-element , >> tuple-pattern-element-list >> - tuple-pattern-element → pattern | identifier:pattern >> + tuple-pattern-element → pattern >> >> <https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#impact-on-existing-code>Impact >> on Existing Code >> >> Because very little code is intentionally using Tuple Shuffles, impact on >> existing code will be negligible but not non-zero. >> >> >> <https://github.com/CodaFi/swift-evolution/blob/8eaf320b3c2a117909fc0269c398e89c033a4b9f/proposals/NNNN-deprecate-tuple-shuffles.md#alternatives-considered>Alternatives >> considered >> >> Continue to keep the architecture in place to facilitate this feature. >> _______________________________________________ >> swift-evolution mailing list >> swift-evolution@swift.org <mailto:swift-evolution@swift.org> >> https://lists.swift.org/mailman/listinfo/swift-evolution >> <https://lists.swift.org/mailman/listinfo/swift-evolution> >
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