[swift-evolution] Pitch: Member lookup on String should not find members of NSString

Jonathan Hull jhull at gbis.com
Tue Oct 24 17:09:53 CDT 2017

I would feel better about it if String gained a lot of the utility of NSString (so that we don’t have to go to NSString all the time for methods)


> On Oct 24, 2017, at 3:00 PM, Slava Pestov via swift-evolution <swift-evolution at swift.org> wrote:
> Hi,
> Members of NSString, except those defined in Foundation, are available on values of type String. For example,
> extension NSString {
>  @objc func foo() {}
> }
> let s: String = “hello”
> s.foo()
> We don’t do this for any other bridged types, for instance NSArray methods are not imported as Array methods. It’s literally a special case in the type checker for member lookup on String.
> This behavior doesn’t really much sense conceptually and it was put in as a stop-gap in Swift 1 to beef up the String API. I would like to phase it out as follows:
> - Unconditional warning in Swift 4.1, with a fixit to insert an ‘as NSString’ cast
> - Error in Swift 5 with -swift-version 5
> What does everyone think about this?
> Slava
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