> On Jul 4, 2017, at 5:48 PM, Jacob Bandes-Storch <[email protected]> wrote:
>
> On Tue, Jul 4, 2017 at 7:21 AM, David Baraff <[email protected]
> <mailto:[email protected]>> wrote:
>
> func decoded(_ input: Any) -> Set {
> if let listVal = input as? [Set.Element] {
> return Set(listVal)
> }
> return self
> }
>
>
> This looks a little weird — what is `self` here? It might be more appropriate
> to use a `static func` or even a failable `init?`.
Yes, it is weird. What’s going on is this: we invoke the decoded function in
the protocol by writing
defaultValue.decoded(someObscureAny)
in this case, we’re saying “take my Any, and give me back the same type of
thing as defaultValue, but if you can’t, then give me back defaultValue”. So
now you’ve imparted the type information of defaultValue to be able to call the
correct function. And i agree this is strange. i’d much rather have
static func decoded(_ input:Any, defaultValue:Set) -> Set {
}
but when I tried that, I got a compiler error about needing to do something
which has type constraints. I think a static function in the protocol doesn’t
lock things down enough?
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