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[Rule Request] Prefer new block based KVO API in Swift 3.2 or 4 #1714

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marcelofabri opened this Issue Jul 27, 2017 · 3 comments

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marcelofabri commented Jul 27, 2017

When using Swift 3.2 or 4, the new block based API KVO API is preferred.

kvo

// should trigger
func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {

}

// ok
let observer = foo.observe(\.value, options: [.new]) { (foo, change) in
    print(change.newValue)
}
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marcelofabri Jul 27, 2017

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Probably the most trick thing here is to detect the Swift version.

We can the new keypath syntax and the structure to find if it's Swift >= 3.2.

  • file.swift
let nameKeyPath = \ForceUser.name
  • Command
    sourcekitten structure --file file.swift

  • Result with Swift 3.1:

{
  "key.offset" : 0,
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.length" : 34,
  "key.diagnostics" : [
    {
      "key.filepath" : "\/Users\/marcelofabri\/dev\/SwiftLint\/file.swift",
      "key.column" : 19,
      "key.description" : "invalid character in source file",
      "key.fixits" : [
        {
          "key.offset" : 18,
          "key.sourcetext" : " ",
          "key.length" : 1
        }
      ],
      "key.line" : 1,
      "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
      "key.severity" : "source.diagnostic.severity.error"
    }
  ],
  "key.substructure" : [
    {
      "key.nameoffset" : 4,
      "key.accessibility" : "source.lang.swift.accessibility.internal",
      "key.length" : 33,
      "key.name" : "nameKeyPath",
      "key.kind" : "source.lang.swift.decl.var.global",
      "key.namelength" : 11,
      "key.offset" : 0
    }
  ]
}
  • Result with Swift 3.2 or 4:
{
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.substructure" : [
    {
      "key.nameoffset" : 4,
      "key.accessibility" : "source.lang.swift.accessibility.internal",
      "key.length" : 33,
      "key.name" : "nameKeyPath",
      "key.kind" : "source.lang.swift.decl.var.global",
      "key.namelength" : 11,
      "key.offset" : 0
    }
  ],
  "key.offset" : 0,
  "key.length" : 34
}

Unfortunately, I couldn't find a way do identify whether it's Swift 3.2 or 4.

Collaborator

marcelofabri commented Jul 27, 2017

Probably the most trick thing here is to detect the Swift version.

We can the new keypath syntax and the structure to find if it's Swift >= 3.2.

  • file.swift
let nameKeyPath = \ForceUser.name
  • Command
    sourcekitten structure --file file.swift

  • Result with Swift 3.1:

{
  "key.offset" : 0,
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.length" : 34,
  "key.diagnostics" : [
    {
      "key.filepath" : "\/Users\/marcelofabri\/dev\/SwiftLint\/file.swift",
      "key.column" : 19,
      "key.description" : "invalid character in source file",
      "key.fixits" : [
        {
          "key.offset" : 18,
          "key.sourcetext" : " ",
          "key.length" : 1
        }
      ],
      "key.line" : 1,
      "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
      "key.severity" : "source.diagnostic.severity.error"
    }
  ],
  "key.substructure" : [
    {
      "key.nameoffset" : 4,
      "key.accessibility" : "source.lang.swift.accessibility.internal",
      "key.length" : 33,
      "key.name" : "nameKeyPath",
      "key.kind" : "source.lang.swift.decl.var.global",
      "key.namelength" : 11,
      "key.offset" : 0
    }
  ]
}
  • Result with Swift 3.2 or 4:
{
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.substructure" : [
    {
      "key.nameoffset" : 4,
      "key.accessibility" : "source.lang.swift.accessibility.internal",
      "key.length" : 33,
      "key.name" : "nameKeyPath",
      "key.kind" : "source.lang.swift.decl.var.global",
      "key.namelength" : 11,
      "key.offset" : 0
    }
  ],
  "key.offset" : 0,
  "key.length" : 34
}

Unfortunately, I couldn't find a way do identify whether it's Swift 3.2 or 4.

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ornithocoder Jul 27, 2017

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Maybe using #if swift()?

$ swift --version
Apple Swift version 3.1 (swiftlang-802.0.53 clang-802.0.42)
Target: x86_64-apple-macosx10.9
$ cat file.swift 
#if swift(>=3.1)
    print("3.1.x")
#endif
$ sourcekitten structure --file file.swift
{
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.substructure" : [
    {
      "key.namelength" : 5,
      "key.nameoffset" : 21,
      "key.length" : 14,
      "key.name" : "print",
      "key.bodyoffset" : 27,
      "key.bodylength" : 7,
      "key.kind" : "source.lang.swift.expr.call",
      "key.offset" : 21
    }
  ],
  "key.offset" : 0,
  "key.length" : 43
}
$ cat file.swift 
#if swift(>=4.0)
    print("4.0.x")
#endif
$ sourcekitten structure --file file.swift
{
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.substructure" : [

  ],
  "key.offset" : 0,
  "key.length" : 43
}
Contributor

ornithocoder commented Jul 27, 2017

Maybe using #if swift()?

$ swift --version
Apple Swift version 3.1 (swiftlang-802.0.53 clang-802.0.42)
Target: x86_64-apple-macosx10.9
$ cat file.swift 
#if swift(>=3.1)
    print("3.1.x")
#endif
$ sourcekitten structure --file file.swift
{
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.substructure" : [
    {
      "key.namelength" : 5,
      "key.nameoffset" : 21,
      "key.length" : 14,
      "key.name" : "print",
      "key.bodyoffset" : 27,
      "key.bodylength" : 7,
      "key.kind" : "source.lang.swift.expr.call",
      "key.offset" : 21
    }
  ],
  "key.offset" : 0,
  "key.length" : 43
}
$ cat file.swift 
#if swift(>=4.0)
    print("4.0.x")
#endif
$ sourcekitten structure --file file.swift
{
  "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse",
  "key.substructure" : [

  ],
  "key.offset" : 0,
  "key.length" : 43
}
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marcelofabri Jul 27, 2017

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@ornithocoder Nice! Unfortunately, we still can't tell if it's 3.2 or 4. But I guess in most cases it won't matter anyway. We can leave that for later if needed.

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marcelofabri commented Jul 27, 2017

@ornithocoder Nice! Unfortunately, we still can't tell if it's 3.2 or 4. But I guess in most cases it won't matter anyway. We can leave that for later if needed.

marcelofabri added a commit that referenced this issue Jul 27, 2017

marcelofabri added a commit that referenced this issue Jul 27, 2017

marcelofabri added a commit that referenced this issue Jul 27, 2017

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