[swift-users] Using ... as a concrete type conforming to protocol ... is not supported

[Hooman Mehr]

Oops! that is buggy. I should check syntax before posting…

Here is the corrected version:

public struct AnyKey : Hashable {
    
    public let hashValue: Int
    public let key: Any
    public let equals: (Any, AnyKey) -> Bool
    
    init<T: Hashable>(_ key: T) {
        
        self.hashValue = key.hashValue
        self.key = key
        self.equals = { $0 as! T == $1.key }
    }
}

public func == (lhs: AnyKey, rhs: AnyKey) -> Bool { return lhs.equals(lhs,rhs) }


> On Mar 25, 2016, at 5:59 PM, Hooman Mehr via swift-users <swift-users at swift.org> wrote:
> 
> You can also get a heterogenous dictionary, but it needs a type erasing helper box. With the following declarations:
> 
> public func ==<T: Equatable>(lhs: T, rhs: Any) -> Bool {
>     
>     if let rhs = rhs as? T { return lhs == rhs } else { return false }
> }
> 
> public struct AnyKey : Hashable {
>     
>     public let hashValue: Int
>     public let key: Any
>     public let equals: (AnyKey) -> Bool
>     
>     init<T: Hashable>(_ key: T) {
>         
>         self.hashValue = key.hashValue
>         self.key = key
>         self.equals = { self.key as! T == $0.key }
>     }
> }
> 
> public func == (lhs: AnyKey, rhs: AnyKey) -> Bool { lhs.equals(rhs) }
> 
> You can now create a heterogenous [AnyKey: Any] dictionary. Note that `AnyKey` is not very memory efficient.
> 
>> On Mar 25, 2016, at 5:27 PM, Hooman Mehr <hooman at mac.com <mailto:hooman at mac.com>> wrote:
>> 
>> 
>>> On Mar 25, 2016, at 2:51 PM, Jason Sadler via swift-users <swift-users at swift.org <mailto:swift-users at swift.org>> wrote:
>>> 
>>> (My particular use case can be seen here: https://gist.github.com/sadlerjw/2cc16b4375b02fe7f400 <https://gist.github.com/sadlerjw/2cc16b4375b02fe7f400> … and the best information I’ve been able to find on this so far is here: http://stackoverflow.com/questions/33112559/protocol-doesnt-conform-to-itself/33524927#33524927 <http://stackoverflow.com/questions/33112559/protocol-doesnt-conform-to-itself/33524927#33524927>)
>> 
>> Here is the best you can do for your particular use case:
>> 
>> protocol AnyEquatable { func equals(other: Any) -> Bool }
>> 
>> func ==<T: Equatable>(lhs: T, rhs: Any) -> Bool {
>>     
>>     if let rhs = rhs as? T { return lhs == rhs } else { return false }
>> }
>> 
>> extension Bool:   AnyEquatable { func equals(other: Any) -> Bool { return self == other } }
>> 
>> extension Int:    AnyEquatable { func equals(other: Any) -> Bool { return self == other } }
>> 
>> extension Double: AnyEquatable { func equals(other: Any) -> Bool { return self == other } }
>> 
>> extension String: AnyEquatable { func equals(other: Any) -> Bool { return self == other } }
>> 
>> extension Array {
>>     
>>     func indexOfAny(element : AnyEquatable) -> Index? { return indexOf { element.equals($0) } }
>> }
>> 
>> var array: [Any] = [false, 1, 2.0, "three"]
>> 
>> array.indexOfAny(2.0)
>> 
> 
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