[swift-evolution] [Proposal] Factory Initializers

Nicholas Maccharoli nmaccharoli at gmail.com
Mon Mar 20 22:09:53 CDT 2017

+ IntMax.max

On Tue, Mar 21, 2017 at 12:07 PM, Greg Parker via swift-evolution <
swift-evolution at swift.org> wrote:

> On Mar 17, 2017, at 9:26 AM, Riley Testut via swift-evolution <
> swift-evolution at swift.org> wrote:
> Hi again everyone!
> Now that Swift 4 Stage 2 proposals are being considered, I thought it
> might be time to revisit this proposal and see if it might align with the
> goals set forth for Swift 4.
> As a quick tl;dr, this proposal describes a new "factory initializer" that
> would allow you to return a value from an initializer. This would have
> several benefits, as mentioned in the proposal itself as well as throughout
> this mailing list. For convenience, here's a link to the proposal on
> GitHub: https://github.com/rileytestut/swift-evolution/
> blob/master/proposals/NNNN-factory-initializers.md
> Would love to hear any more comments on this proposal, and if we feel this
> is appropriate for considering for Swift 4 I'll happily re-open the pull
> request!
> "As for overriding, just like convenience initializers, factory
> initializers should not be able to be overridden by subclasses."
> This needs more explanation. It is allowed for a subclass to implement a
> convenience initializer that has the same signature as a superclass
> convenience initializer or a superclass designated initializer. The
> convenience-over-convenience case is not technically overriding, but it is
> misleading to say only that a convenience initializer cannot be overridden.
> Do factory initializers follow exactly the same rules here as convenience
> initializers?
> In addition: designated initializers and convenience initializers have
> rules about which other initializers can be called from an implementation.
> These rules are intended to guarantee that the chain of designated
> initializers is called correctly. What are the precise rules for factory
> initializers calling other initializers? What are the precise rules for
> non-factory initializers calling factory initializers?
> --
> Greg Parker     gparker at apple.com     Runtime Wrangler
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
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