[swift-evolution] Pitch: really_is and really_as operators

[Xiaodi Wu]

On Wed, Aug 24, 2016 at 10:07 PM, Charles Srstka <cocoadev at charlessoft.com>
wrote:

> 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>
>  wrote:
>
>> On Aug 24, 2016, at 9:51 PM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
>>
>> On Wed, Aug 24, 2016 at 9:47 PM, Xiaodi Wu <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?
>

This is where I'm out of my depth, but I'll take a stab at it:
I _think_ the metatype itself is bridgeable, but it can't lie about the
type-of-which-the-metatype-is-the-type.


> Charles
>
>
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