I think I like this, but what about guard?
func f(x: Int) -> Int {
guard x > 0 else { return 0 }
...
}
vs
func f(x: Int) -> Int {
guard x > 0 else { 0 }
...
}
?
On 17.02.2017 11:20, Adrian Zubarev via swift-evolution wrote:
I’d like to revive an additive proposal that couldn’t make it into Swift 3.
This proposal has a small improvement to the language compared to other big
features currently being proposed. It almost feels like a bug fix rather
than a new feature, but it still needs a full and quick review process.
You can read the formatted version here:
https://github.com/apple/swift-evolution/pull/608
|return| consistency for single-expressions
* Proposal: SE-NNNN
<https://github.com/apple/swift-evolution/blob/master/proposals/nnnn-single-expression-optional-return.md>
* Author: Adrian Zubarev <https://github.com/DevAndArtist>
* Status: *Awaiting review*
* Review manager: TBD
Introduction
Any single-expression closure can omit the |return| statement. This
proposal aims to make this feature more consistent in some other corners of
the language.
Original swift-evolution thread: * [Pitch] [Stage–2] |return| consistency
for single-expressions * [Pitch] (Bofore Swift 3) Make |return| optional in
computed properties for a single case
<https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160523/019260.html>
Motivation
Closures can omit the |return| and have an inferred return type:
|let _ = { 42 } // Type: () -> Int let _ = [1,2,3].map { $0 * 5 } // T == Int |
There are also value returning code blocks in the language that feel the
same but are inconsistent to the mentioned feature:
|// Read-write computed property: var integer: Int { get { return 2016 } set
{ /* do some work */ } } // Read-only computed property: var string: String
{ return "hello swift" } // Function: func pi() -> Double { return 3.141 }
// Read-Write subscript: subscript(index: Int) -> Int { get { return index
% 2 } set { /* do some work */ } } // Read-only subscript: subscript(index:
Int) -> Int { return index * 2 } |
Proposed solution
Make |return| optional for the following top level code blocks that only
contain a single expression:
* /variable-declaration/
* /getter-setter-block/
* /getter-clause/
* /function-body/
* /subscript-declaration/
That will allow us to rewrite the above example to:
|// Read-Write computed property: var integer: Int { get { 2016 } ... } //
Read-only computed property: var string: String { "hello swift" } //
Function: func pi() -> Double { 3.141 } // Read-Write subscript:
subscript(index: Int) -> Int { get { index % 2 } ... } // Read-only
subscript: subscript(index: Int) -> Int { index * 2 } |
*Possible real world example:*
|// Today public struct Character { public let source: Module.Source private
let _pointer: UnsafePointer<Swift.Character> public var value:
Swift.Character { return self._pointer.pointee } ... } // Rewritten: public
struct Character { ... public var value: Swift.Character {
self._pointer.pointee } ... } |
Impact on existing code
None, this change will only relax some existing rules.
Alternatives considered
Leave this as is and live with such inconsistency.
--
Adrian Zubarev
Sent with Airmail
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