[swift-corelibs-dev] Mark NSUnimplemented functions as unavailable.

Tony Parker anthony.parker at apple.com
Wed May 10 18:41:54 CDT 2017

Hi Sergej,

This is a good idea, but there are some additional things to consider. In some cases, methods are partially unimplemented (with edge cases, or at least less common cases remaining unfinished). The availability macro can’t reflect that status.

In other cases, we want to partially implement one function but still call through to an unimplemented function. The entire call may fail with the assert, but at least we have part of the implementation in place.

- Tony

> On May 10, 2017, at 4:01 PM, Sergej Jaskiewicz via swift-corelibs-dev <swift-corelibs-dev at swift.org> wrote:
> I was wondering why cannot we just mark all the methods/properties/functions in Swift Foundation that are NSUnimplemented or call a subroutine that is NSUnimplemented like this:
> @available(*, unavailable, message: “foo is not implemented yet”)
> func foo() { NSUnimplemented() }
> In this case we can be sure at compile time that we don’t use code that will definitely crash.
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