[swift-evolution] [Proposal] Uniform Initialization Syntax

Greg Parker gparker at apple.com
Thu Jun 8 23:45:27 CDT 2017

> On Jun 8, 2017, at 5:09 AM, Gor Gyolchanyan via swift-evolution <swift-evolution at swift.org> wrote:
> 1. Arbitrary `self` Assignments In Intializers
> The first ideas is to allow `self = nil` inside failable initializers (essentially making `self` look like `inout Self?` instead of `inout Self` with magical `return nil`), so that all initializers uniformly can be written in `self = ...` form for clarity and convenience purposes. This should, theoretically, be nothing but a `defer { return nil }` type of rewrite, so I don't see any major difficulties implementing this. This is especially useful for failable-initializing enums where the main switch simply assigns to self in all cases and the rest of the initializer does some post-processing.

I don't see how to avoid source incompatibility and uglification of failable initializer implementations here. Allowing `self = nil` inside a failable initializer would require `self` to be an optional. That in turn would require every use of `self` in the initializer to be nil-checked or forced. I don't think that loss everywhere outweighs the gain of `self = nil` in some places.

Greg Parker     gparker at apple.com <mailto:gparker at apple.com>     Runtime Wrangler

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