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enum Ͱ Key Paths ͷΑ͏ͳ
ػೳΛ࣮ݱ͢Δ Case Paths
After Party iOSDC Japan 2022
kalupas226
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ࣗݾհ
• ΞΠΧϫ
• @kalupas226
• Cookpad Inc. iOS Developer
2
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ΞδΣϯμ
• Key Paths ͷجຊ
• Case Paths ʹ͍ͭͯ
• Case Paths ͱʁ
• Case Paths ͷجຊͱར༻ྫ
• Case Paths ͷ࣮໘നϙΠϯτ
• Case Paths ͷར༻ʹෆ͕҆͋Δํ
• ·ͱΊ
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Key Paths ͷجຊ
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Key Paths ͱʁ
• Swift Ͱ struct Λੜ͢ΔͱԿͤͣʹར༻Ͱ͖Δπʔϧ
• struct ʹ͓͚Δ struct ࣗͷܕͱ
fi
eld ͷܕใΛදݱͰ͖ΔͨΊ
༷ʑͳ༻్Ͱར༻Ͱ͖Δ
• ׳ΕΔ·Ͱࣗ༝ࣗࡏʹ͏ͷ͕͍͔͠͠Εͳ͍
• SwiftUI, Combine, KeyPath Member Lookup ͳͲͰ
ར༻͞Ε͍ͯΔ
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Key Paths ͷجຊ
struct User {
var id: Int
var name: String
var address: Address?
}
var user = User(
id: 42,
name: "kalupas",
address: .init(street: "ͩ͜͜Α")
)
// user[keyPath: \.id] Ͱ OK
user[keyPath: \User.id] // 42
user[keyPath: \.id] = 57
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Key Paths ͷجຊ
struct User {
var id: Int
var name: String
var address: Address?
}
var user = User(
id: 42,
name: "kalupas",
address: .init(street: "ͩ͜͜Α")
)
// user[keyPath: \.id] Ͱ OK
user[keyPath: \User.id] // 42
user[keyPath: \.id] = 57
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Key Paths ͷجຊ
struct User {
var id: Int
var name: String
var address: Address?
}
var user = User(
id: 42,
name: "kalupas",
address: .init(street: "ͩ͜͜Α")
)
// user[keyPath: \.id] Ͱ OK
user[keyPath: \User.id] // 42
user[keyPath: \.id] = 57
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Key Paths ͷجຊ
struct User {
var id: Int
var name: String
var address: Address?
}
var user = User(
id: 42,
name: "kalupas",
address: .init(street: "ͩ͜͜Α")
)
// user[keyPath: \.id] Ͱ OK
user[keyPath: \User.id] // 42
user[keyPath: \.id] = 57
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͜Ε͚ͩͩͱ Key Paths ͷࢫຯ͕ͳ͍
user[keyPath: \.id] // 42
user[keyPath: \.id] = 57
! dot syntax Ͱ༻Ͱ͖Δ
user.id // 42
user.id = 57
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Key Paths ͷخ͠͞ΛҰ෦ൈਮͯ͠հ
• ӳจͷΑ͏ͳߏจʹͰ͖Δ
• Ҿͱͯ͠ getter ͱ setter Λඞཁͱ͢ΔγʔϯͰҾΛ
ίϯύΫτʹͰ͖Δ
• map ͳͲͷߴ֊ؔͰར༻Ͱ͖Δ
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Key Paths ͷخ͠͞ΛҰ෦ൈਮͯ͠հ
• ӳจͷΑ͏ͳߏจʹͰ͖Δ
• Ҿͱͯ͠ getter ͱ setter Λඞཁͱ͢ΔγʔϯͰҾΛ
ίϯύΫτʹͰ͖Δ
• map ͳͲͷߴ֊ؔͰར༻Ͱ͖Δ
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ӳจͷΑ͏ͳߏจʹ / ҾΛίϯύΫτʹ Ͱ͖Δ
class Label {
var text = ""
var fontSize = 12
}
class ProductModel {
var name = "kalupas"
}
let model = ProductModel()
let label = Label()
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Label ʹ ProductModel ͷ property Λ bind ͢Δ
class Label {
var text = ""
var fontSize = 12
}
class ProductModel {
var name = "kalupas"
}
let model = ProductModel()
let label = Label()
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Label ʹ ProductModel ͷ property Λ bind ͢Δ
class Label {
var text = ""
var fontSize = 12
}
class ProductModel {
var name = "kalupas"
}
let model = ProductModel()
let label = Label()
bind(model, \.name, to: label, \.text)
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Label ʹ ProductModel ͷ property Λ bind ͢Δ
class Label {
var text = ""
var fontSize = 12
}
class ProductModel {
var name = "kalupas"
}
let model = ProductModel()
let label = Label()
bind(model, \.name, to: label, \.text)
• ӳจͷΑ͏ʹಡΊΔ
• Bind model name to label text
• getter, setter Λ؆ܿʹهड़Ͱ͖Δ
• \.name = KeyPath (getter)
• \.text = ReferenceWritableKeyPath (getterɾsetter)
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Key Paths ͷخ͠͞ΛҰ෦ൈਮͯ͠հ
• ӳจͷΑ͏ͳߏจʹͰ͖Δ
• Ҿͱͯ͠ getter ͱ setter Λඞཁͱ͢ΔγʔϯͰҾΛ
ίϯύΫτʹͰ͖Δ
• map ͳͲͷߴ֊ؔͰར༻Ͱ͖Δ
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map ͳͲͷߴ֊ؔͰར༻Ͱ͖Δ
struct User {
var name: String
}
let users = [
.init(...),
.init(...),
// ...
]
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map ͳͲͷߴ֊ؔͰར༻Ͱ͖Δ
struct User {
var name: String
}
let users = [
.init(...),
.init(...),
// ...
]
let userNames = users.map { $0.name }
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map ͳͲͷߴ֊ؔͰར༻Ͱ͖Δ
struct User {
var name: String
}
let users = [
.init(...),
.init(...),
// ...
]
let userNames = users.map(\.name)
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map ͳͲͷߴ֊ؔͰར༻Ͱ͖Δ
struct User {
var name: String
}
let users = [
.init(...),
.init(...),
// ...
]
let userNames = users.map(\.name)
0249-key-path-literal-function-
expressions ʹΑ࣮ͬͯݱ͞Εͨ
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ͪΖΜଞʹ Key Paths ͕༗༻ͳ໘͋Δ
• ෳࡶͳϓϩύςΟͷΞΫηε
• KeyPath Member Lookup Λར༻ͨ͠ܕ҆શͳϓϩύςΟͷΞΫηε
• SwiftUI
• ʮ@StateʯΛʮ$user.nameʯͷΑ͏ʹѻ͑Δ
• ʮ@Environment(\.dismiss)ʯ
• ForEach ͳͲͰΑ͘ݟ͔͚Δʮ\.selfʯ(Identity key path) ͳͲ
• ଞʹࢁ͋Δͱࢥ͍·͕͢ɺհ͖͠Εͳ͍ͷͰׂѪ͠·͢
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Case Paths ʹ͍ͭͯ
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Case Paths ͱʁ
• Point-Free ͷϥΠϒϥϦ
• https://github.com/pointfreeco/swift-case-paths
• struct → Key Paths, enum → Case Paths
• enum Ͱ Key Paths ͷΑ͏ͳػೳ͕͑Δ
• Key Paths ʮ\ʯͰΞΫηε͢Δ͕ɺCase Paths ʮ/ʯ
• ݩʑ Mirror Λͬͨ Re
fl
ection ʹΑΓ࣮͞Ε͍͕ͯͨɺݱࡏ Swift ͷ
Pointer Λར༻͍ͯ͠ΔͷͰ Mirror ΑΓ҆શͳ࣮ํ๏ʹมΘ͍ͬͯΔ
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Case Paths ͷجຊ
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
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Case Paths ͷجຊ
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
/Authentication.authenticated // CasePath
ʮ/Enum.Caseʯͱ͍͏ߏจͰ
CasePath ΛखʹೖΕΒΕΔ
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enum ʹ associated value ΛೖΕ͍ͨ࣌ (௨ৗ)
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let authentication = Authentication.authenticated(
accessToken: "cafebeef"
)
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enum ʹ associated value ΛೖΕ͍ͨ࣌ (௨ৗ)
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let authentication = Authentication.authenticated(
accessToken: "cafebeef"
)
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enum ͷ associated value ΛऔΓग़͍ͨ࣌͠ (௨ৗ)
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let authentication = Authentication.authenticated(
accessToken: "cafebeef"
)
if case let .authenticated(accessToken) = authentication {
// use accessToken
}
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enum ͷ associated value ΛऔΓग़͍ͨ࣌͠ (௨ৗ)
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let authentication = Authentication.authenticated(
accessToken: "cafebeef"
)
if case let .authenticated(accessToken) = authentication {
// use accessToken
}
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Case Paths Λͬͯ associated value ΛೖΕΔ
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let authentication = Authentication.authenticated(
accessToken: "cafebeef"
)
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Case Paths Λͬͯ associated value ΛೖΕΔ
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
// let authentication = Authentication.authenticated(
// accessToken: "cafebeef"
// )
let authentication = (/Authentication.authenticated).embed("cafebeef")
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Case Paths Ͱ associated value ΛऔΓग़͢
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let authentication = (/Authentication.authenticated).embed(“cafebeef")
if case let .authenticated(accessToken) = authentication {
// use accessToken
}
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Case Paths Ͱ associated value ΛऔΓग़͢
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let authentication = (/Authentication.authenticated).embed(“cafebeef")
// if case let .authenticated(accessToken) = authentication {
// // use accessToken
// }
(/Authentication.authenticated).extract(from: authentication)
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Case Paths ͷଞͷػೳ - Composition -
\HighScore.user.name
// WritableKeyPath
/Result..Authentication.authenticated
// CasePath, String>
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Case Paths ͷଞͷػೳ - Identity case path -
\User.self // WritableKeyPath
/Authentication.self // CasePath
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Case Paths ͷར༻ํ๏
• Key Paths ͱಉ͘͡ɺgetterɾsetter ͚ͩͷׂͰ Case Paths Λ
ར༻ͯ͠ࢫຯΛಘΒΕΔέʔεগͳ͍
• Caes Paths ͷར༻ྫΛݟ͍ͯ͘͜ͱͰศར͞Λগ͚ͩ͠հ͢Δ
• map ͳͲͷߴ֊ؔͰͷར༻
• swiftui-navigation
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map ͳͲͷߴ֊ؔͰͷར༻
// Key Paths
users.map(\User.name)
// Case Paths
authentications.compactMap(/Authentication.authenticated)
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map ͳͲͷߴ֊ؔͰͷར༻
// Key Paths
users.map(\User.name)
// Case Paths
authentications.compactMap(/Authentication.authenticated)
Case Paths ͷॲཧɺcase ʹ associated value ͕
ଘࡏ͠ͳ͍߹ nil ʹͳΔͨΊɺcompactMap ͳͲΛར༻͢Δ
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swiftui-navigation
• Point-Free ͷ SwiftUI Navigation ʹ focus ͨ͠ϥΠϒϥϦ
• https://github.com/pointfreeco/swiftui-navigation
• iOSDC Japan 2022 Ͱൃදͨ͠ͷͰৄͦͪ͘͠ΒΛࢀর͍ͩ͘͞🙏
• ʮSwiftUI Navigation ͷͯ͢ʯ
• swiftui-navigation ͷ෦Ͱ Case Paths ͕ར༻͞Ε͍ͯΔ
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swiftui-navigation
struct ContentView: View {
enum Route {
case create
case draft(Post)
}
@State var route: Route?
var body: some View {
BaseView(...)
.sheet(
unwrapping: $route,
case: /Route.draft
) { $draft in
EditPostView(post: $draft)
}
}
}
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swiftui-navigation
struct ContentView: View {
enum Route {
case create
case draft(Post)
}
@State var route: Route?
var body: some View {
BaseView(...)
.sheet(
unwrapping: $route,
case: /Route.draft
) { $draft in
EditPostView(post: $draft)
}
}
}
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swiftui-navigation
struct ContentView: View {
enum Route {
case create
case draft(Post)
}
@State var route: Route?
var body: some View {
BaseView(...)
.sheet(
unwrapping: $route,
case: /Route.draft
) { $draft in
EditPostView(post: $draft)
}
}
}
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swiftui-navigation
extension View {
func sheet(
unwrapping enum: Binding,
case casePath: CasePath,
@ViewBuilder content: @escaping (Binding) -> Content
) -> some View where Content: View {
self.sheet(
isPresented: `enum`.case(casePath).isPresented()
) {
Binding(
unwrapping: `enum`.case(casePath)
).map(content)
}
}
}
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Case Paths ͷ͓͔͛Ͱ enum ͷಛఆͷ case ʹ
Ԡͨ͡ॲཧΛهड़Ͱ͖ΔΑ͏ʹͳΔ
extension View {
func sheet(
unwrapping enum: Binding,
case casePath: CasePath,
@ViewBuilder content: @escaping (Binding) -> Content
) -> some View where Content: View {
self.sheet(
isPresented: `enum`.case(casePath).isPresented()
) {
Binding(
unwrapping: `enum`.case(casePath)
).map(content)
}
}
}
Enum ͷಛఆͷ case ͕
active ͳ࣌ʹͷΈ
දࣔ͞ΕΔ sheet
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Case Paths ͷ࣮໘നϙΠϯτ
• pre
fi
x, in
fi
x operator
• @_disfavoredOverload
• Mirror
• Pointer
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Case Paths ͷ࣮໘നϙΠϯτ
• pre
fi
x, in
fi
x operator
• @_disfavoredOverload
• Mirror
• Pointer
• ࠓͷൃද·Ͱʹઆ໌Ͱ͖ΔϨϕϧ·Ͱམͱ͠ࠐΊͳ͔ͬͨͷͰɺ
·ͨͷػձʹهࣄʹ͢Δ͔ൃද͠Α͏ͱࢥ͍·͢🙇
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Case Paths ͷ࣮໘നϙΠϯτ
• pre
fi
x, in
fi
x operator
• @_disfavoredOverload
• Mirror
• Pointer
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pre
fi
x, in
fi
x operator
• pre
fi
x: ಄ࣙ
• in
fi
x: தࣙ
• post
fi
x (ඌࣙ) ͋Δ͕ɺͦΕར༻͞Ε͍ͯͳ͍ͷͰׂѪ
• pre
fi
x operator ͷྫ
• Key Paths ʹ͓͚Δʮ\User.idʯɺBoolean ͷసʮ!isPresentedʯͳͲ
• in
fi
x operator ͷྫ
• ʮ1 + 2ʯʮ2 - 1ʯͳͲ
• operator ࣗ࡞͢Δ͜ͱ͕Ͱ͖Δ
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Case Paths ʹ͓͚Δ pre
fi
x operatorʮ/ʯͷࣗ࡞
prefix operator /
public prefix func / (
embed: @escaping (Value) -> Root
) -> CasePath {
.init(embed: embed, extract: extractHelp(embed))
}
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Case Paths ʹ͓͚Δ pre
fi
x operatorʮ/ʯͷࣗ࡞
prefix operator /
public prefix func / (
embed: @escaping (Value) -> Root
) -> CasePath {
.init(embed: embed, extract: extractHelp(embed))
}
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Case Paths ʹ͓͚Δ pre
fi
x operatorʮ/ʯͷࣗ࡞
prefix operator /
public prefix func / (
embed: @escaping (Value) -> Root
) -> CasePath {
.init(embed: embed, extract: extractHelp(embed))
}
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Case Paths ʹ͓͚Δ pre
fi
x operatorʮ/ʯͷࣗ࡞
prefix operator /
public prefix func / (
embed: @escaping (Value) -> Root
) -> CasePath {
.init(embed: embed, extract: extractHelp(embed))
}
/Authentication.authenticated
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embed: (Value) -> Root ʹ
Authentication.authenticated ΛͤΔཧ༝
embed: @escaping (Value) -> Root
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let auth = Authentication.authenticated // (String) -> Authentication
// (String) -> Authentication
// (Value) -> Root
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embed: (Value) -> Root ʹ
Authentication.authenticated ΛͤΔཧ༝
embed: @escaping (Value) -> Root
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let auth = Authentication.authenticated // (String) -> Authentication
// (String) -> Authentication
// (Value) -> Root
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embed: (Value) -> Root ʹ
Authentication.authenticated ΛͤΔཧ༝
embed: @escaping (Value) -> Root
enum Authentication {
case authenticated(accessToken: String)
case unauthenticated
}
let auth = Authentication.authenticated // (String) -> Authentication
// (String) -> Authentication
// (Value) -> Root
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Case Paths ʹ͓͚Δ in
fi
x operatorʮ..ʯͷࣗ࡞
precedencegroup CasePathCompositionPrecedence {
associativity: left
}
infix operator ..: CasePathCompositionPrecedence
extension CasePath {
public static func .. (
lhs: CasePath,
rhs: @escaping (AppendedValue) -> Value
) -> CasePath {
lhs.appending(path: /rhs)
}
}
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Case Paths ʹ͓͚Δ in
fi
x operatorʮ..ʯͷࣗ࡞
precedencegroup CasePathCompositionPrecedence {
associativity: left
}
infix operator ..: CasePathCompositionPrecedence
extension CasePath {
public static func .. (
lhs: CasePath,
rhs: @escaping (AppendedValue) -> Value
) -> CasePath {
lhs.appending(path: /rhs)
}
}
precedencegroup Ͱ operator ʹ
ϧʔϧΛ࣋ͨͤΔ͜ͱ͕Ͱ͖Δ
associativity: leftͰ
operator ʹࠨ݁߹ͷ݁߹ੑΛ࣋ͨͤΒΕΔ
(1 + 2) + 3 Ͱͳ͘ 1 + 2 + 3
Ͱߦ͚ΔΑ͏ʹ͢ΔΠϝʔδ
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Case Paths ʹ͓͚Δ in
fi
x operatorʮ..ʯͷࣗ࡞
precedencegroup CasePathCompositionPrecedence {
associativity: left
}
infix operator ..: CasePathCompositionPrecedence
extension CasePath {
public static func .. (
lhs: CasePath,
rhs: @escaping (AppendedValue) -> Value
) -> CasePath {
lhs.appending(path: /rhs)
}
}
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Case Paths ʹ͓͚Δ in
fi
x operatorʮ..ʯͷࣗ࡞
precedencegroup CasePathCompositionPrecedence {
associativity: left
}
infix operator ..: CasePathCompositionPrecedence
extension CasePath {
public static func .. (
lhs: CasePath,
rhs: @escaping (AppendedValue) -> Value
) -> CasePath {
lhs.appending(path: /rhs)
}
}
/Result .. Authentication.authenticated
lhs rhs
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Case Paths ͷ࣮໘നϙΠϯτ
• pre
fi
x, in
fi
x operator
• @_disfavoredOverload
• Mirror
• Pointer
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Swift Ͱ function overload ͕ڐ͞Ε͍ͯΔ
func sameName() {}
func sameName(value: Int) {}
func sameName() {}
func sameName(value: Int = 5) {}
func sameName(_ number: Int) {}
func sameName(_ number: N) {}
func sameName(_ number: Int) {}
func sameName(_ numbers: Int...) {}
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overload ͞Ε͍ͯΔ߹ɺΑΓ۩ମతͳͷ͕
༏ઌ͞ΕͯݺΕΔ (ެࣜʹݴٴ͞Ε͍ͯͳ͍)
func sameName() {}
func sameName(value: Int = 5) {}
func sameName(_ number: Int) {}
func sameName(_ number: N) {}
func sameName(_ number: Int) {}
func sameName(_ numbers: Int...) {}
https://forums.swift.org/t/compiler-choosing-between-functions-with-no-parameters-vs-functions-with-default-parameters/23501/2
https://www.
fi
vestars.blog/articles/disfavoredOverload/
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overload ͞Ε͍ͯΔ߹ɺΑΓ۩ମతͳͷ͕
༏ઌ͞ΕͯݺΕΔ (ެࣜʹݴٴ͞Ε͍ͯͳ͍)
func sameName() {} // sameName() Ͱͪ͜Β͕ݺΕΔ
func sameName(value: Int = 5) {}
func sameName(_ number: Int) {} // sameName(5) Ͱͪ͜Β͕ݺΕΔ
func sameName(_ number: N) {}
func sameName(_ number: Int) {} // sameName(5) Ͱͪ͜Β͕ݺΕΔ
func sameName(_ numbers: Int...) {}
https://forums.swift.org/t/compiler-choosing-between-functions-with-no-parameters-vs-functions-with-default-parameters/23501/2
https://www.
fi
vestars.blog/articles/disfavoredOverload/
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sameName(value:) Λ༏ઌͯ͠ݺͤΔํ๏
func sameName() {} // sameName() Ͱͪ͜Β͕ݺΕΔ
func sameName(value: Int = 5) {}
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sameName(value:) Λ༏ઌͯ͠ݺͤΔํ๏
@_disfavoredOverload
func sameName() {}
func sameName(value: Int = 5) {} // sameName() Ͱͪ͜Β͕ݺΕΔΑ͏ʹͳΔ
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sameName(value:) Λ༏ઌͯ͠ݺͤΔํ๏
@_disfavoredOverload
func sameName() {}
func sameName(value: Int = 5) {} // sameName() Ͱͪ͜Β͕ݺΕΔΑ͏ʹͳΔ
`@_disfavoredOverload` ʹʮ_ (ΞϯμʔείΞ)ʯ͕
͍͍ͯΔͷɺSwift Evolution Λ௨ա͍ͯ͠ͳ͍ͨΊɻ
Library headers ʹ `@_disfavoredOverload` Ͱ͋Δ͜ͱ͕
දࣔ͞Εͳ͍ͨΊɺdocument comment Λ͚ͭΔ͜ͱ͕ॏཁ
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Case Paths Ͱ @_disfavoredOverload ͕
ར༻͞Ε͍ͯΔ
public prefix func / (
embed: @escaping (Value) -> Root
) -> CasePath {
.init(embed: embed, extract: extractHelp(embed))
}
@_disfavoredOverload
public prefix func / (
embed: @escaping (Value) -> Root
) -> (Root) -> Value? {
(/embed).extract(from:)
}
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Case Paths Ͱ @_disfavoredOverload ͕
ར༻͞Ε͍ͯΔ
public prefix func / (
embed: @escaping (Value) -> Root
) -> CasePath {
.init(embed: embed, extract: extractHelp(embed))
}
@_disfavoredOverload
public prefix func / (
embed: @escaping (Value) -> Root
) -> (Root) -> Value? {
(/embed).extract(from:)
}
ීஈ `/Authentication.authenticated` ͷΑ͏ʹ
ར༻ͨ͠߹ɺ্ͷ function ͕༏ઌ͞ΕͯݺΕΔ
`compactMap` ͳͲͰར༻ͨ࣌͠
= `(Root) -> Value?` Λඞཁͱ͢Δ࣌
ͷΈͰԼͷ function ͕ݺΕΔΑ͏ʹͳ͍ͬͯΔ
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Case Paths ͷ࣮໘നϙΠϯτ
• pre
fi
x, in
fi
x operator
• @_disfavoredOverload
• Mirror
• Pointer
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Mirror
• ݩʑ Case Paths ͷ෦࣮ʹ Mirror ͕ར༻͞Ε͍ͯͨ
• ݱࡏ Pointer Λར༻ͨ͠ Mirror ΑΓ҆શͳ࣮ํ๏ʹͳ͍ͬͯΔ
• https://github.com/pointfreeco/swift-case-paths/pull/37
• Mirror Swift Ͱ Re
fl
ection Λߦ͑Δ API
• Re
fl
ection: ϓϩάϥϜͷதͰͦͷϓϩάϥϜʹؚ·ΕΔܕ
ม/ϝιουͷใΛࢀর/ૢ࡞Ͱ͖ΔΑ͏ʹ͢ΔΈ
• Mirror ͷڍಈอূ͞Ε͍ͯͳ͍ͨΊɺར༻ʹҙ͕ඞཁ (جຊతʹσόοά༻్͘Β͍
Ͱར༻ͨ͠ํ͕ྑ͍)
71
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struct Ͱ Mirror Λར༻͢ΔҰྫ
struct User {
var id: Int
var name: String
var address: Address?
}
let user = User(id: 1, name: "kalupas", address: .init(street: "street"))
func allProperties(_ value: Any) -> [String] {
Mirror(reflecting: value).children.compactMap { $0.label }
}
print(allProperties(user))
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struct Ͱ Mirror Λར༻͢ΔҰྫ
struct User {
var id: Int
var name: String
var address: Address?
}
let user = User(id: 1, name: "kalupas", address: .init(street: "street"))
func allProperties(_ value: Any) -> [String] {
Mirror(reflecting: value).children.compactMap { $0.label }
}
print(allProperties(user))
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struct Ͱ Mirror Λར༻͢ΔҰྫ
struct User {
var id: Int
var name: String
var address: Address?
}
let user = User(id: 1, name: "kalupas", address: .init(street: "street"))
func allProperties(_ value: Any) -> [String] {
Mirror(reflecting: value).children.compactMap { $0.label }
}
print(allProperties(user))
dump(Mirror(reflecting: value).children.first!)
▿ (2 elements)
▿ label: Optional("id")
- some: "id"
- value: 1
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struct Ͱ Mirror Λར༻͢ΔҰྫ
struct User {
var id: Int
var name: String
var address: Address?
}
let user = User(id: 1, name: "kalupas", address: .init(street: "street"))
func allProperties(_ value: Any) -> [String] {
Mirror(reflecting: value).children.compactMap { $0.label }
}
print(allProperties(user)) // ["id", "name", "address"]
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enum Ͱ Mirror Λར༻͢ΔҰྫ
enum Authentication {
case authenticated(String)
case unauthenticated
}
let auth = Authentication.authenticated("deadbeef")
let mirror = Mirror(reflecting: auth)
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enum Ͱ Mirror Λར༻͢ΔҰྫ
enum Authentication {
case authenticated(String)
case unauthenticated
}
let auth = Authentication.authenticated("deadbeef")
let mirror = Mirror(reflecting: auth)
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enum Ͱ Mirror Λར༻͢ΔҰྫ
enum Authentication {
case authenticated(String)
case unauthenticated
}
let auth = Authentication.authenticated("deadbeef")
let mirror = Mirror(reflecting: auth)
dump(mirror.children.first!)
▿ (2 elements)
▿ label: Optional("authenticated")
- some: "authenticated"
- value: "deadbeef"
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Case Paths Ͱͷ Mirror ͷར༻ྫΛݟͯΈΔ
enum Authentication {
case authenticated(String)
case unauthenticated
}
let auth = Authentication.authenticated("deadbeef")
extract(case: Authentication.authenticated, from: auth)
// Optional(“deadbeef") ͕खʹೖΔ
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Case Paths Ͱͷ Mirror ͷར༻ྫΛݟͯΈΔ
enum Authentication {
case authenticated(String)
case unauthenticated
}
let auth = Authentication.authenticated("deadbeef")
extract(case: Authentication.authenticated, from: auth)
// Optional(“deadbeef") ͕खʹೖΔ
※ ͜ͷ extract function આ໌ͷͨΊͷͷͰ͋ΓɺCase Paths ʹଘࡏ͍ͯ͠ͳ͍
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Mirror ʹΑΔ extract ͷ࣮ํ๏
(આ໌ͷͨΊͷෆશͳ࣮ʣ
func extract(
case: @escaping (Value) -> Root,
from root: Root
) -> Value? {
let mirror = Mirror(reflecting: root)
guard let child = mirror.children.first else { return nil }
guard let value = child.value as? Value else { return nil }
let newRoot = `case`(value)
let newMirror = Mirror(reflecting: newRoot)
guard let newChild = newMirror.children.first else { return nil }
guard newChild.label == child.label else { return nil }
return value
}
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Mirror ʹΑΔ extract ͷ࣮ํ๏
(આ໌ͷͨΊͷෆશͳ࣮ʣ
func extract(
case: @escaping (Value) -> Root,
from root: Root
) -> Value? {
let mirror = Mirror(reflecting: root)
guard let child = mirror.children.first else { return nil }
guard let value = child.value as? Value else { return nil }
let newRoot = `case`(value)
let newMirror = Mirror(reflecting: newRoot)
guard let newChild = newMirror.children.first else { return nil }
guard newChild.label == child.label else { return nil }
return value
}
let auth = Authentication.authenticated("deadbeef")
extract(case: Authentication.authenticated, from: auth)
-> Optional(“deadbeef”)
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Mirror ʹΑΔ extract ͷ࣮ํ๏
(આ໌ͷͨΊͷෆશͳ࣮ʣ
func extract(
case: @escaping (Value) -> Root,
from root: Root
) -> Value? {
let mirror = Mirror(reflecting: root)
guard let child = mirror.children.first else { return nil }
guard let value = child.value as? Value else { return nil }
let newRoot = `case`(value)
let newMirror = Mirror(reflecting: newRoot)
guard let newChild = newMirror.children.first else { return nil }
guard newChild.label == child.label else { return nil }
return value
}
dump(mirror.children.first!)
▿ (2 elements)
▿ label: Optional("authenticated")
- some: "authenticated"
- value: "deadbeef"
child
value
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Mirror ʹΑΔ extract ͷ࣮ํ๏
(આ໌ͷͨΊͷෆશͳ࣮ʣ
func extract(
case: @escaping (Value) -> Root,
from root: Root
) -> Value? {
let mirror = Mirror(reflecting: root)
guard let child = mirror.children.first else { return nil }
guard let value = child.value as? Value else { return nil }
let newRoot = `case`(value)
let newMirror = Mirror(reflecting: newRoot)
guard let newChild = newMirror.children.first else { return nil }
guard newChild.label == child.label else { return nil }
return value
}
extract(case: Authentication.authenticated, from: auth)
newRoot = Authentication.authenticated("deadbeef")
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Mirror ʹΑΔ extract ͷ࣮ํ๏
(આ໌ͷͨΊͷෆશͳ࣮ʣ
func extract(
case: @escaping (Value) -> Root,
from root: Root
) -> Value? {
let mirror = Mirror(reflecting: root)
guard let child = mirror.children.first else { return nil }
guard let value = child.value as? Value else { return nil }
let newRoot = `case`(value)
let newMirror = Mirror(reflecting: newRoot)
guard let newChild = newMirror.children.first else { return nil }
guard newChild.label == child.label else { return nil }
return value
}
label ͕ਖ਼͍͜͠ͱΛνΣοΫ
நग़Ͱ͖ͨ value Λฦ͢
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ҙͷ enum ͷ associated value Λ
நग़Ͱ͖ΔΑ͏ʹͳͬͨ
extract(case: Authentication.authenticated, from: auth) // AccessToken
extract(case: Authentication.authenticated, from: .unauthenticated) // nil
extract(case: Result.success, from: .success(42)) // 42
struct MyError: Error {}
extract(case: Result.failure, from: .failure(MyError()))
// MyError
extract(case: Example.foo, from: .foo(2)) // 2
extract(case: Example.bar, from: .foo(2)) // nil
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Case Paths ͷར༻ʹෆ͕҆͋Δํ
• Swift ͕ఏڙͯ͘͠Εͳ͍ͷΛఏڙͰ͖ΔΑ͏ʹ͢ΔͨΊʹɺCase Paths Pointer Λར༻ͯ͠ػೳΛ࣮ݱ͍ͯ͠Δ
• ͳ͘ಈ࡞͢ΔΑ͏ʹɺϕϯνϚʔΫςετڍಈΛอূ͢ΔͨΊͷϢχοτςετ͕༻ҙ͞Ε͍ͯΔ
• ϕϯνϚʔΫςετ: https://github.com/pointfreeco/swift-case-paths/blob/
7346701ea29da0a85d4403cf3d7a589a58ae3dee/Sources/swift-case-paths-benchmark/main.swift
• Ϣχοτςετ: https://github.com/pointfreeco/swift-case-paths/blob/
7346701ea29da0a85d4403cf3d7a589a58ae3dee/Tests/CasePathsTests/CasePathsTests.swift
• ଟͷར༻࣮͋Δ
• ݴޠʹΈࠐ·ΕΔ͜ͱ͕͔ͳΓظ͞Ε͍ͯͯಈ͖׆ൃͳ༷ࢠ
• https://forums.swift.org/t/discussion-inclusion-of-casepaths-into-the-language/53024
• https://github.com/apple/swift/pull/58940
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Case Paths ͷར༻ʹෆ͕҆͋Δํ
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·ͱΊ
• struct ʹ͓͚Δ Key Paths ͷΑ͏ͳػೳΛ enum Ͱ࣮ݱ͢Δ Case Paths ͱ͍͏ϥΠϒϥϦ͕ Point-Free ʹΑͬͯ
ఏڙ͞Ε͍ͯΔ
• Case Paths ʹ༷ʑͳར༻γʔϯ͕͋Δ
• map ͳͲͷߴ֊ؔͰͷར༻ɺfunction ͷҾͱͯ͠ಛఆͷ case Λ׆༻͍ͨ͠߹ͳͲ
• Case Paths ͷ࣮ͰҎԼͷΑ͏ͳٕज़͕ར༻͞Ε͍ͯΔ
• pre
fi
x, in
fi
x operator
• @_disfavoredOverload
• Mirror (ࠓར༻͞Ε͍ͯͳ͍)
• Pointer
• Case Paths ͔ͬ͠Γςετ͞Ε͍ͯͯར༻࣮͋ΓɺݴޠػೳʹΈࠐΉͷͨΊͷಈ͖ൃੜ͍ͯ͠Δ
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ࢀߟ
• Case Paths पล
• https://github.com/pointfreeco/swift-case-paths
• https://github.com/wickwirew/Runtime
• https://github.com/pointfreeco/swiftui-navigation
• https://forums.swift.org/t/discussion-inclusion-of-casepaths-into-the-language/53024
• Mirror
• https://developer.apple.com/documentation/swift/mirror
• https://qiita.com/bannzai/items/96b912a9db43cefdb728
• Pointer
• https://developer.apple.com/documentation/swift/unsafepointer
• https://qiita.com/omochimetaru/items/c95e0d36ae7f1b1a9052
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ࢀߟ
• pre
fi
x, in
fi
x operator
• https://docs.swift.org/swift-book/LanguageGuide/BasicOperators.html
• https://docs.swift.org/swift-book/LanguageGuide/AdvancedOperators.html
• disfavoredOverload
• https://www.
fi
vestars.blog/articles/disfavoredOverload/
• Key Paths पล
• proposals
• https://github.com/apple/swift-evolution/blob/main/proposals/0161-key-paths.md
• https://github.com/apple/swift-evolution/blob/main/proposals/0227-identity-keypath.md
• https://github.com/apple/swift-evolution/blob/master/proposals/0249-key-path-literal-function-expressions.md
• https://github.com/apple/swift-evolution/blob/main/proposals/0252-keypath-dynamic-member-lookup.md
• https://www.youtube.com/watch?v=-eRhuwAZyCU
• https://www.pointfree.co/episodes/ep8-getters-and-key-paths
• https://www.pointfree.co/episodes/ep7-setters-and-key-paths
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ิࢿྉ
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Key Paths ΛΘͣʹಉ͡දݱΛ͢Δʹʁ
bind(model, \.name, to: label, \.text)
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Key Paths ΛΘͣʹಉ͡දݱΛ͢Δʹʁ
bind(model, \.name, to: label, \.text)
!
bind(
model: model,
get: { $0.name },
to: label,
get: { $0.text },
set: { $0.text = $1 }
)
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Key Paths ΛΘͣʹಉ͡දݱΛ͢Δʹʁ
bind(model, \.name, to: label, \.text)
!
bind(
model: model,
get: { $0.name },
to: label,
get: { $0.text },
set: { $0.text = $1 }
)
• ӳจͷΑ͏ʹಡΊͳ͍
• getter, setter Λදݱ͢ΔͨΊʹ
Ҿ͕ଟ͘ͳΔ
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bind ͷྫͷ߹ɺҎԼͷΑ͏ʹͰ͖Δ
bind(
model: model,
get: { $0.name },
to: label,
get: { $0.text },
set: { $0.text = $1 }
)
!
bind(model.name, to: label)
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Combine ͰࣅͨΑ͏ͳߏจ͕͋Δ
let subject = PassthroughSubject()
subject.assign(to: \.text, on: label)
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Combine ͰࣅͨΑ͏ͳߏจ͕͋Δ
let subject = PassthroughSubject()
subject.assign(to: \.text, on: label)
• ӳจͷΑ͏ʹಡΊΔ
• Ҿ͕ίϯύΫτʹͳΔ