[swift-evolution] Pitch: really_is and really_as operators

Charles Srstka cocoadev at charlessoft.com
Wed Aug 24 22:07:32 CDT 2016

> On Aug 24, 2016, at 10:00 PM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
> On Wed, Aug 24, 2016 at 9:58 PM, Charles Srstka <cocoadev at charlessoft.com <mailto:cocoadev at charlessoft.com>> wrote:
>> On Aug 24, 2016, at 9:51 PM, Xiaodi Wu <xiaodi.wu at gmail.com <mailto:xiaodi.wu at gmail.com>> wrote:
>> On Wed, Aug 24, 2016 at 9:47 PM, Xiaodi Wu <xiaodi.wu at gmail.com <mailto:xiaodi.wu at gmail.com>> wrote:
>> Works on Linux :)
>> And besides, on any platform where `type(of: bar) != NSString`, why should you expect `bar really_is NSString == true`? Isn't bar *not really* NSString?
> Because the pitch was for a version of ‘is’ which lacks the Objective-C bridging. The ‘is’ keyword matches subclasses of the type you specify as well as the type itself.
> Sorry, I corrected myself :) I neglected the part where you mentioned that __NSCFString is a subclass of NSString (which I forgot was the case). But as you can see, `type(of: bar) is NSString.Type` works just fine :)

Yeah, it does; thanks. I thought that ‘is’ on the type would be compromised in the same way as it normally is, so it’s good to know that there’s a way to make it honest. I still hate the bridging, and wish that SE-0083 were not apparently dead, but grumble grumble grumble, at least there’s a workaround. Is this documented anywhere?


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