For what it’s worth, if T is a reference type or Unsafe*Pointer, then T and Optional<T> have the same exact representation in memory.
The compiler is smart enough to know that a non-optional pointer can never be NULL, so a NULL value of the underlying type can be used to unambiguously encode the ‘none’ case. This is not the case with Optional<NSRect> for example, where every bit pattern represents a potentially valid NSRect value, so Optional<NSRect> has to add an extra tag byte to distinguish the two enum cases from each other. Slava > On Jan 10, 2017, at 9:52 AM, Rien via swift-users <swift-users@swift.org> > wrote: > > I stand corrected. > > I do/did think that there is a difference in the way it handles pointers > optionals and other optionals, but I now realise that even that could not be > the case. > So please ignore the last line in my previous post. > > The rest still stand ;-) > > Regards, > Rien > > Site: http://balancingrock.nl > Blog: http://swiftrien.blogspot.com > Github: http://github.com/Swiftrien > Project: http://swiftfire.nl > > > > >> On 10 Jan 2017, at 18:14, Joe Groff <jgr...@apple.com> wrote: >> >> >>> On Jan 9, 2017, at 11:19 PM, Rien via swift-users <swift-users@swift.org> >>> wrote: >>> >>> It means that a call to that function with an optional will unwrap the >>> optional before it is used. >>> >>> That is quite neat when dealing with C-API’s because often you will receive >>> a pointer from a C-function which is optional to account for the fact that >>> it can be NULL (= nil). >>> By using a forced unwrapped input parameter you are saved the trouble of >>> unwrapping all these pointers when using them as input for other C-APIs. >>> >>> In short, it makes it easier to interface with C-API’s. >>> >>> Note that there is some under-the-hood magic going on because a C-pointer >>> is an unboxed value, while a ‘normal’ optional is a boxed value. >> >> Optionals are never boxed. >> >> -Joe > > _______________________________________________ > swift-users mailing list > swift-users@swift.org > https://lists.swift.org/mailman/listinfo/swift-users _______________________________________________ swift-users mailing list swift-users@swift.org https://lists.swift.org/mailman/listinfo/swift-users
