[swift-evolution] [SHORT Review] SE-0134: Rename two UTF8-related properties on String

[Xiaodi Wu]

Ben, while I'm broadly sympathetic to making CChar work more widely, if I
recall correctly this was a rather complex discussion topic you're raising
again. Besides the unprecedented name (Unsigned is never spelled out at the
moment), I wonder if all the other salient issues involved are best left
for a wider discussion than is possible here, especially since the pitch
and proposal have been limited to two properties.
On Wed, Jul 27, 2016 at 07:33 Ben Rimmington via swift-evolution <
swift-evolution at swift.org> wrote:

>
> > On 25 Jul 2016, at 15:27, Ben Rimmington wrote:
> >
> > <
> https://github.com/apple/swift-evolution/blob/master/proposals/0134-rename-string-properties.md
> >
> >
> > My suggestion for SE-0134 is to use the `utf8CString` name, overloading
> for CSignedChar and CUnsignedChar:
> >
> >       <
> https://github.com/apple/swift/blob/master/stdlib/public/core/CString.swift
> >
> >
> >       extension String {
> >       - init(cString: UnsafePointer<CChar>)
> >       - init(cString: UnsafePointer<UInt8>)
> >       - init?(validatingUTF8 cString: UnsafePointer<CChar>)
> >
> >       + init(utf8CString: UnsafePointer<CSignedChar>)
> >       + init(utf8CString: UnsafePointer<CUnsignedChar>)
> >       + init?(validatingUTF8CString: UnsafePointer<CSignedChar>)
> >       + init?(validatingUTF8CString: UnsafePointer<CUnsignedChar>)
> >       }
> >
> > The properties would change to methods, overloaded by return type:
> >
> >       <
> https://github.com/apple/swift/blob/master/stdlib/public/core/StringUTF8.swift
> >
> >
> >       extension String {
> >       - var nulTerminatedUTF8CString: ContiguousArray<CChar>
> >       - var nulTerminatedUTF8: ContiguousArray<UTF8.CodeUnit>
> >
> >       + func utf8CString() -> ContiguousArray<CSignedChar>
> >       + func utf8CString() -> ContiguousArray<CUnsignedChar>
> >       }
> >
> > ## NOTES ##
> >
> > UTF8.CodeUnit is defined as UInt8, and CChar is currently defined as
> Int8:
> >
> >       <
> https://github.com/apple/swift/blob/master/stdlib/public/core/CTypes.swift
> >
> >
> >       /// The C 'char' type.
> >       ///
> >       /// This will be the same as either `CSignedChar` (in the common
> >       /// case) or `CUnsignedChar`, depending on the platform.
> >       public typealias CChar = Int8
> >
> >       /// The C 'signed char' type.
> >       public typealias CSignedChar = Int8
> >
> >       /// The C 'unsigned char' type.
> >       public typealias CUnsignedChar = UInt8
> >
> > There's an abandoned proposal to update CChar:
> >
> >       <
> http://thread.gmane.org/gmane.comp.lang.swift.evolution/7925/focus=8158>
> >
> >       <http://thread.gmane.org/gmane.comp.lang.swift.evolution/8419>
> >
> > String.init(cString: UnsafePointer<UInt8>) and nulTerminatedUTF8CString
> were added by SE-0107:
> >
> >       <
> https://github.com/apple/swift-evolution/blob/master/proposals/0107-unsaferawpointer.md#cstring-conversion
> >
> >
> >       <
> https://github.com/apple/swift/commit/c7aa8284c905a73959ad69255cb56c38db80d039
> >
> >
> > Foundation.NSString uses the `utf8String` name instead:
> >
> >       <
> https://developer.apple.com/reference/foundation/nsstring/1412128-init>
> >
> >       <
> https://developer.apple.com/reference/foundation/nsstring/1411189-utf8string
> >
>
> <
> https://github.com/apple/swift-evolution/blob/master/proposals/0134-rename-string-properties.md
> >
>
> There's another method for SE-0134 which could be renamed or removed:
>
>         <
> https://github.com/apple/swift/blob/master/stdlib/public/core/LifetimeManager.swift
> >
>
>         extension String {
>         - func withCString<Result>(
>         -   _ body: @noescape (UnsafePointer<Int8>) throws -> Result
>         - ) rethrows -> Result
>
>         + func withUTF8CString<Result>(
>         +   _ body: @noescape (UnsafePointer<CSignedChar>) throws -> Result
>         + ) rethrows -> Result
>
>         + func withUTF8CString<Result>(
>         +   _ body: @noescape (UnsafePointer<CUnsignedChar>) throws ->
> Result
>         + ) rethrows -> Result
>         }
>
> The overloads (CSignedChar and CUnsignedChar) are needed if CChar will
> become UInt8 on some platforms.
>
> -- Ben
>
> _______________________________________________
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> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
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