[swift-evolution] [Late Pitch] Deprecations, Moves, and Renames
davesweeris at mac.com
Tue Aug 9 15:59:49 CDT 2016
Sent from my iPhone
> On Aug 9, 2016, at 14:09, Dave Abrahams via swift-evolution <swift-evolution at swift.org> wrote:
> Hi Everybody,
> With another round of apologies for taking late action, we propose to
> make some deprecations, moves, and renames. The background for these
> moves is as follows:
> We've always known that when Swift reached ABI stability (now slated for
> Swift 4), we would be committed to supporting many of the standard
> library's design decisions for years to come. What we only realized
> very recently is that, although Swift 3.0 is *not* shipping with a
> stable ABI, the promise that Swift 3.0 code will work with Swift 4.0
> code creates similar implications when it comes to certain protocols,
> today. Especially where these protocols show up in refinement
> hierarchies, we can't keep Swift 3 code working in the future without
> carrying them forward into future libraries.
> The proposed changes are as follows:
> * Move `CustomPlaygroundQuickLookable` to the PlaygroundSupport module.
> This component is really only useful for playgrounds, and doesn't
> belong in the standard library.
> * Deprecate the Indexable protocols with a message indicating that they
> will be gone in Swift 4. These protocols are implementation details
> of the standard library designed to work around language limitations
> that we expect to be gone in Swift 4. There's no reason for anyone to
> ever touch these; users should always use a corresponding Collection
> protocol (e.g. instead of MutableIndexable, use MutableCollection).
> * Deprecate the ExpressibleByStringInterpolation protocol with a
> message indicating that its design is expected to change. We know
> this protocol to be mis-designed
> (https://bugs.swift.org/browse/SR-1260) and limited
> (https://bugs.swift.org/browse/SR-2303), but there's no time to fix it
> for Swift 3. If we knew what the new design should look like, we
> might be able to calculate that the current API is supportable in a
> forward-compatible way (as we do for Comparable). Unfortunately, we
> do not.
> * Rename Streamable to TextOutputStreamable and add a deprecated
> Streamable typealias for it. Now that OutputStream been renamed to
> TextOutputStream, we should also move Streamable out of the way.
> Deprecation is being proposed instead of underscoring or renaming
> because it allows existing code to keep working (with warnings). At
> this late stage, it would be bad to actually break anything.
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