Conform BirdBush to Codable only when its wrapped type is Codable

[ZevEisenberg]

You might be able to find some good uses of conditional conformance here: https://github.com/davecom/SwiftGraph

Something like:

extension BirdBush: Codable where U: Codable {
    // I forget if the compiler will do the work for you, or if you’ll have to write the conformance yourself
}

[hsnetzer]

Thanks for the suggestion, Zev.

[ZevEisenberg]

Hey, @hsnetzer,

There’s a subtle issue with the way this is implemented now: BirdBush only exists where U is Codable, which effectively comes to the same problem as before: you can’t use it except with Codable types. I think you want something like this:

class BirdBush<U> {
    ...
}

extension BirdBush: Codable where U: Codable {
    ...
}

This way, you can use BirdBush with any type you want, and if you happen to use it with a Codable type, it will become Codable automatically. You can read more about conditional conformance here: https://swift.org/blog/conditional-conformance/

Enjoy 😉

[hsnetzer]

Ah, thanks again! the where clause would probably cause an error when initializing with anything but codable types. I’ll fix this tomorrow.

[hsnetzer]

a3b1db0

This implements the conditional conformance we want. As a consequence of adding conformance in an extension, I did have to mark BirdBush as final, which I'm fine with. Otherwise child objects might not actually be codable.