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Swift 4ΛৼΓฦΓ
Swift 5ͷເΛݟΔ
id:ikesyo
Hatena Engineer Seminar #9 @ Tokyo
2017-10-30 Mon
#hatenatech
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id:ikesyo
• ͍͚͠ΐʔʗా ᠳ
• גࣜձࣾͯͳ
• ϒοΫϚʔΫΞϓϦνʔϜ
• Swiftίϛολʔ
• ओઓswift-corelibs-foundation
• http://b.hatena.ne.jp/ikesyo/
• https://twitter.com/ikesyo
• https://github.com/ikesyo
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Agenda
• Swift 4.0
• Swift 4.1
• Swift 5.0
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Swift 4.0
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Swift 4.0
https://swift.org/blog/swift-4-0-released/
• September 2017
• ABI Stability is deferred to Swift 5
• Two language modes
• Swift 3.2
• Swift 4.0
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Swift 4.0
https://swift.org/blog/swift-source-compatibility-test-suite/
• Source Compatibility Test Suite
• https://swift.org/source-compatibility/
• https://github.com/apple/swift-source-compat-suite
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Swift 4.0
• 30 proposals are implemented
• https://apple.github.io/swift-
evolution/#?version=4
• And SE-0161
• Smart KeyPaths: Better Key-Value
Coding for Swift
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Codable
• SE-0166 Swift Archival & Serialization
• Automatic requirements synthesis (can be overridden by
a manual implementation)
• DerivedConformanceCodable.cpp
• DerivedConformanceCodingKey.cpp
• SE-0167 Swift Encoders
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Codable
struct User: Codable {
let id: String
let name: String
let age: Int
}
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Codable
let json = """
{
"id": "123",
"name": "Foo Bar",
"age": 24
}
""".data(using: .utf8)!
let decoder = JSONDecoder()
let decodedUser = try decoder.decode(User.self, from: json)
let encoder = JSONEncoder()
let encodedUserData: Data = try encoder.encode(decodedUser)
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Codable
Decodable
struct User: Codable {
...
private enum CodingKeys: String, CodingKey {
case id, name, age
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
id = try container.decode(String.self, forKey: .id)
name = try container.decode(String.self, forKey: .name)
age = try container.decode(Int.self, forKey: .age)
}
}
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Codable
Encodable
struct User: Codable {
...
private enum CodingKeys: String, CodingKey {
case id, name, age
}
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(id, forKey: .id)
try container.encode(name, forKey: .name)
try container.encode(age, forKey: .age)
}
}
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Codable
• https://github.com/norio-nomura/ObjectEncoder
• Swift Encoders implementation using [String: Any],
[Any] or Any as payload.
• May be useful for migrating from existing JSON
decoders/mappers
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Smart KeyPaths
• SE-0161 Smart KeyPaths: Better Key-Value Coding for Swift
struct Presenter {
var order: Int
var name: String
}
var p = Presenter(order: 2, name: "ikesyo")
p[keyPath: \Presenter.order] // 2
p[keyPath: \Presenter.name] = "ా ᠳ"
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Smart KeyPaths
KeyPath chain
struct Foo {
let bar: Bar?
}
struct Bar {
let baz: Baz
}
struct Baz {
let value: Int
}
// Optional chaining
\Foo.bar?.baz.value // KeyPath
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Smart KeyPaths
Class hierarchy
class AnyKeyPath { ... }
class PartialKeyPath: AnyKeyPath { ... }
class KeyPath: PartialKeyPath { ... }
class WritableKeyPath: KeyPath { ... }
class ReferenceWritableKeyPath: WritableKeyPath { ... }
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Smart KeyPaths
• https://github.com/kishikawakatsumi/Kuery
• https://github.com/kishikawakatsumi/RealmTypeSafeQuery
• [SR-5220] Expose API to retrieve string representation of
KeyPath - Swift
• _kvcKeyPathString
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The Law of Exclusivity
• SE-0176 Enforce Exclusive Access to Memory
• Required for ABI Stability
• Ownership Manifesto
• @omochimetaru Swift ʹಋೖ༧ఆͷ Ownership ػೳͷ
հ - Qiita (Swift Tweets 2017 Fall)
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The Law of Exclusivity
var x = 0, y = 0
// NOT A CONFLICT. These two accesses to 'x' are both reads.
// Each completes instantaneously, so the accesses do not overlap and
// therefore do not conflict. Even if they were not instantaneous, they
// are both reads and therefore do no conflict.
let z = x + x
// NOT A CONFLICT. The right-hand side of the assignment is a read of
// 'x' which completes instantaneously. The assignment is a write to 'x'
// which completes instantaneously. The accesses do not overlap and
// therefore do not conflict.
x = x
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The Law of Exclusivity
// NOT A CONFLICT. The right-hand side is a read of 'x' which completes
// instantaneously. Calling the operator involves passing 'x' as an inout
// argument; this is a write access for the duration of the call, but it does
// not begin until immediately before the call, after the right-hand side is
// fully evaluated. Therefore the accesses do not overlap and do not conflict.
x += x
// CONFLICT. Passing 'x' as an inout argument is a write access for the
// duration of the call. Passing the same variable twice means performing
// two overlapping write accesses to that variable, which therefore conflict.
swap(&x, &x)
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The Law of Exclusivity
extension Int {
mutating func assignResultOf(_ function: () -> Int) {
self = function()
}
}
// CONFLICT. Calling a mutating method on a value type is a write access
// that lasts for the duration of the method. The read of 'x' in the closure
// is evaluated while the method is executing, which means it overlaps
// the method's formal access to 'x'. Therefore these accesses conflict.
x.assignResultOf { x + 1 }
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Swift 4.1
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Swift 4.1
https://swift.org/blog/swift-4-1-release-process/
Swift 4.1 is not binary compatible with 4.0. It contains a
variety of under-the-hood changes that are part of the
effort to stabilize the Swift ABI in Swift 5.
• The first half of 2018
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Implemented proposals (as of Oct 30)
• SE-0075 Adding a Build Configuration Import Test
#if canImport(UIKit)
// UIKit-based code
#elseif canImport(Cocoa)
// OSX code
#elseif
// Workaround/text, whatever
#endif
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Implemented proposals (as of Oct 30)
• SE-0185 Synthesizing Equatable and Hashable
conformance
• DerivedConformanceEquatableHashable.cpp
• SE-0186 Remove ownership keyword support in protocols
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Features that may be added
• SE-0157 Support recursive constraints on associated types
// Will not currently compile
protocol Sequence {
associatedtype SubSequence: Sequence
where Iterator.Element == SubSequence.Iterator.Element, SubSequence.SubSequence ==
SubSequence
// Returns a subsequence containing all but the first 'n' items
// in the original sequence.
func dropFirst(_ n: Int) -> Self.SubSequence
// ...
}
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Features that may be added
• SE-0143 Conditional conformances
• Generics Manifesto
extension Array: Equatable where Element: Equatable
{
static func ==(lhs: Array, rhs:
Array) -> Bool { ... }
}
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Swift 5.0
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Swift 5.0
https://github.com/apple/swift-evolution/blob/master/README.md
• Expected release date: Late 2018
• Primary Focus: ABI Stability
• Swift ABI Stability Manifesto
• ABI Dashboard
• Generics features needed for standard library, API resilience,
Memory ownership model (carried over from Swift 4)
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Swift 5.0
• Other Improvements
• String ergonomics
• Improvements to existing standard library facilities
• Foundation improvements
• Syntactic additions
• Laying groundwork for a new concurrency model
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String ergonomics
• String Manifesto
String re-evaluation: String is one of the most important
fundamental types in the language. The standard library
leads have numerous ideas of how to improve the
programming model for it, without jeopardizing the
goals of providing a unicode-correct-by-default model.
Our goal is to be better at string processing than Perl!
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Laying groundwork for a new concurrency
model
• Async/Await for Swift
• https://gist.github.com/lattner/
429b9070918248274f25b714dcfc7619
• @koher Proposalʹࡌ͍ͬͯͳ͍Swift 5ͷasync/await͕ૉΒ͍͠ͱ
ࢥ͏ཧతഎܠ - Qiita (Swift Tweets 2017 Fall)
• Concurrency in Swift: One approach
• https://gist.github.com/lattner/31ed37682ef1576b16bca1432ea9f782
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Proposals (as of Oct 30)
These seem to be related to ABI stability and API resilience.
• [Proposal] Non-exhaustive enums #751
• [Proposal] Restrict cross-module struct initializers #753
• [Proposal] Cross-module inlining and specialization #754
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Appendix
• ࣮ફSwiftίϯύΠϥ #swtws - Qiita (Swift Tweets 2017
Summer)
• ຊਓॳͷSwiftίϛολʔͰ͋Δ@rintaro͞ΜʹΑΔSwift
ίϯύΠϥͷίϯτϦϏϡʔτํ๏ͷղઆ
• Swift Tweets 2018 Winter @ 2018-01-20 Sat
• @ikesyoൃද͠·͢
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! Happy Swift Coding!! !
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Thank you❗"
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