> On Feb 28, 2017, at 4:26 PM, Jens Alfke <[email protected]> wrote: > > >> On Feb 28, 2017, at 11:56 AM, Daryle Walker <[email protected] >> <mailto:[email protected]>> wrote: >> >> The problem here is an interface mismatch where Swift has function >> throw-ability status out-of-band from that function’s parameter list, while >> Objective-C doesn’t. > > Only at the syntax level. Under the hood it works basically the same way as > Objective-C, with the error as a hidden ‘out’ parameter. (It pretty much has > to, for interoperability purposes.) > > So an init() method that throws is a different method with a different > signature than one that doesn’t; the two aren’t type-compatible. And I don’t > think the two can coexist in one scope, because they’d be ambiguous at the > call site. So adding a throwing initializer to NSDocument would require > removing the non-throwing one, which can’t be done for backward-compatibility > reasons.
A throwable “init()” would require a “try” in front of it. If Swift bans non-throwable code from being prefixed with “try”, then the two versions could be distinguishable. Can an initializer be used for a closure property (i.e. function pointer)? Then in that case there could be a problem, since non-throwable functions are subsets are throwable ones (so a closure to a throwable method would accept both). > I’m sure there are some hacky special-case workarounds that could be done to > make this work, if this were a really important aspect of the AppKit API. But > I don’t think it is. It may be annoying that the common code shared between > your initializers can’t throw, but there are simple workarounds. — Daryle Walker Mac, Internet, and Video Game Junkie darylew AT mac DOT com _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
