Hello Enrico,
Thank you for the reply!
If the goal of `Mirror` is reflection, wouldn’t the full structure of a type
need to be exposed by its `Mirror`? And even if the goal is a more limited form
of inspection, wouldn’t it still be necessary to make the default
implementation, which exposes all variables, accessible?
(Is there a way to do that – to ignore `customMirror` and get a type’s ‘full’
mirror? If not, I think the exposure of CustomReflectable outside the standard
library is a bit strange.)
Regards,
Will Stanton
> On Sep 23, 2016, at 1:54 PM, Enrico Granata <egran...@apple.com> wrote:
>
> There exists a default behavior, but also an override mechanism
> (CustomReflectable) in case the author of the type knows better
>
> For instance, if you have
>
> struct Point { var x: Double; var y: Double }
>
> you probably do just want to see "x" and "y" reflected - and the default will
> do just that
>
> But in more complex scenarios, e.g. Array<T>, you probably want to see the
> logical contents of the type (the array elements), not the underlying
> implementation details
>
> I don't think metadata currently vends visibility, so it's unlikely we do
> anything to hide non-public variables in reflection.
> I think other languages take a similar stance, so maybe it's just the right
> thing to do, but I also can't recall any explicit discussion about this
>
> As for the Foundation-specific bits, I'll let somebody with more Foundation
> expertise help you out
>
>>
>> With respect to Foundation, I was starting to silence some warnings with ‘as
>> Any’ (https://bugs.swift.org/browse/SR-2737), but I noticed this code in
>> URLComponents.swift at
>> https://github.com/apple/swift-corelibs-foundation/blob/master/Foundation/URLComponents.swift#L313:
>>
>> if let s = self.scheme { c.append((label: "scheme", value: s)) }
>> if let u = self.user { c.append((label: "user", value: u)) }
>> etc...
>>
>>
>> Should public properties be mirrored even if their values are nil?
>> c.append((label: "scheme", value: s as Any))
>> c.append((label: "user", value: u as Any))
>> etc...
>>
>> What rules should there be to determine what gets mirrored?
>>
>> Regards,
>> Will Stanton
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