Any idea why Swift supports implicit casting to AnyHashable, but not to, say, AnySequence?
> > On Aug 18, 2016, at 9:54 AM, Adel Zhang via > > swift-users<swift-users@swift.org>wrote: > > > > Any other situation when implicit type casting works? > I don't know if there's a comprehensive list anywhere. Here are the ones I > can think of: > > 1. A subtype can be used where a supertype is expected; for instance, you can > pass an `Int` to a parameter typed `Any` without a cast. The same is true of > superclasses: `NSString` can be used where `NSObject` is expected. Obvious, > but worth mentioning. > > 2. Swift 3's `AnyHashable` isn't *really* a supertype of `Hashable` types, > but it's sort of treated as one. > > 3. The built-in `Array`, `Dictionary`, `Set`, and `Optional` types can be > implicitly converted to the same data structure, but with supertypes of its > generic parameters. For instance, an `Array<Int>` can be passed to a > parameter of type `Array<Any>`. This is not a general feature of > generics—it's special-cased for these types. > > 4. As you noticed, a type can be implicitly made more `Optional`; that is, > `Int` converts to `Optional<Int>`, `Optional<Optional<Int>>`, and so on. > > 5. In Swift 2, importing Foundation activates many implicit conversions > between Foundation and Standard Library types, including conversions to > AnyObject. Many (perhaps all?) are gone in Swift 3. (However, Foundation > still has plenty of magical `as` casts.) > > Hope this helps, > -- > Brent Royal-Gordon > Architechies > > > > _______________________________________________ swift-users mailing list swift-users@swift.org https://lists.swift.org/mailman/listinfo/swift-users
