Hello,
I have been thinking about a case that is missing completely from swift.
We have the AnyObject type to represent an Object of any type.
I recently run upon a situation where i needed a type to represent any Protocol. A AnyProtocol Type would be useful for my case.
Example:
I have a generic class that needs to receive a protocol type. The code without the AnyProtocol is the following:
public class MulticastDelegate<T> {
private var delegates = NSHashTable.weakObjectsHashTable()
public init() {}
public func addDelegate(delegate: T) {
guard delegate is AnyObject else { return }
delegates.addObject((delegate as! AnyObject))
}
}
This code needs to “trust” that T is a protocol and also make sure T is an Object.
Example using AnyProtocol, if it existed:
public class MulticastDelegate<T:AnyProtocol> {
private var delegates = NSHashTable.weakObjectsHashTable()
public init() {}
public func addDelegate(delegate: T) {
delegates.addObject(delegate)
}
}
Note that the protocol must be a class protocol. This could also be achieved with a where clause or AnyClassProtocol variant.
This example is also available on github: GitHub - jonasman/MulticastDelegate: An elegant multicast delegate written in swift
To extend my proposal, there might be cases where AnyStruct and AnyEnum would be usefull. I have no examples for these cases, but i believe someone might have it.
What are your thoughts, should I open a PR proposal?
João Nunes