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Swift
String Interpolation
USAMI Kosuke
Fenrir Inc.
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String Interpolation
let price = 2
let number = 3
let message = "One cookie: $\(price), \(number) cookies:" +
"$\(price * number)."
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จࣈྻิؒखܰͰศརͰ͢Ͷ
» ͚ͩͲɺϩδοΫ෦ͰΘͳ͍ํ͕͍͍
» URL ͱ͔ΫΤϦͱ͔Ͱආ͚Δ
» ݁Ռ͕༧ଌͮ͠Β͍ͨΊ
» ͋͘·Ͱɺ͓खܰදࣔ༻ͷػೳͰ͋Δ
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จࣈྻิ͕ؒͲͷΑ͏ʹߦΘΕΔ͔
» ExpressibleByStringInterpolation ϓϩτίϧʹઆ໌͕͋Δ
» ·ͣɺϦςϥϧ෦ͱิؒ෦ʹׂ͞ΕΔ
» ͦΕͧΕͷิؒ෦͕ init(stringInterpolationSegment:) ʹ
͞ΕΔ
» ͦΕΒͷ݁Ռ͕ init(stringInterpolation:) ʹ͞ΕΔ
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͜Μͳײ͡
let message = String(stringInterpolation:
String(stringInterpolationSegment: "One cookie: $"),
String(stringInterpolationSegment: price),
String(stringInterpolationSegment: ", "),
String(stringInterpolationSegment: number),
String(stringInterpolationSegment: " cookies: $"),
String(stringInterpolationSegment: price * number),
String(stringInterpolationSegment: "."))
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ExpressibleByStringInterpolation
» ͭ·Γɺ͜ͷϓϩτίϧΛࣗલͰ࣮͢ΕΧελϚΠζͰ͖Δ
» ͔࣮͠͠ɺ͜ΕΛ࣮͢Δඞཁ͋·Γͳ͍ʢޙड़ʣ
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จࣈྻิؒͷσϑΥϧτͷৼΔ͍
» String.init(describing:) Λฦ͢Α͏࣮͞Ε͍ͯΔ
» ͨͩ͠ɺ͍͔ͭ͘ͷϏϧτΠϯܕผ࣮ʢBool ͳͲʣ
» ref : https://github.com/apple/swift/blob/swift-3.0.1-
RELEASE/stdlib/public/core/StringInterpolation.swift.gyb
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String.init(describing:)
» TextOutputStreamable ʹద߹͍ͯͨ͠Β .write(to: s) Λฦ͢
» CustomStringConvertible ʹద߹͍ͯͨ͠Β .description Λฦ͢
» CustomDebugStringConvertible ʹద߹͍ͯͨ͠
Β .debugDescription Λฦ͢
» ͦΕҎ֎ Swift ඪ४ϥΠϒϥϦ͕ࣗಈੜ͢Δ
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ࣗલclassΛจࣈྻิؒʹରԠ͢Δʹ
» ExpressibleByStringInterpolation ͡Όͳ͍͍ͯ͘
» ྫ͑ CustomStringConvertible ͷ .description Λ࣮
» ͩ͜ΘΒͳ͍ͳΒɺඪ४·͔ͤͰग़ྗ͞ΕΔ
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ͱ͜ΖͰ Swift 4 Ͱɾɾɾ
» ExpressibleByStringInterpolation deprecated
» SwiftDoc.org
» Deprecated: it will be replaced or redesigned in Swift 4.0.
Instead of conforming to
'ExpressibleByStringInterpolation', consider adding an
'init(_:String)'.
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Ͳ͏ͳΔͷʁ
» Proposal SE-0137 : Avoiding Lock-In to Legacy Protocol
Designs
» We know this protocol to be mis-designed and limited, but
there's no time to fix it for Swift 3.
» ࠶ઃܭ͞ΕΔ༧ఆΒ͍͠
» Ϧςϥϧ෦ͱิؒ෦ʹׂɺͱ͔ buggy ͳײ͡
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ࢀߟ
» SwiftDoc.org
» github.com/apple/swift
» Swift ͷ Bool ͷจࣈྻදݱͷݴޠ༷ - ja.stackoverflow.com