swiftにおける遅延評価

Transcript

1. TXJGUʹ͓͚Δ
   ஗ԆධՁ $POOFIJUP
   .BSDIÉ
   ˌʙJ04ࢢʙ
   
2. ॴଐɿίωώτגࣜձࣾ
   ۀ຿ɿJ04ΞϓϦ։ൃ
3. ͦ΋ͦ΋
   ஗ԆධՁͱ͸
4. ݁Ռ͕ඞཁʹͳΔ·Ͱؔ਺Λ࣮ߦ͠ͳ͍͜ͱ
   CZ
   ͍͢͝)ຊ
6. class LazyCat { var name = "" lazy var selfIntro: String = { return "໊લ͸\(name)Ͱ͢" }() } let cat = LazyCat() cat.name = "γϩίϚ" print(cat.selfIntro) // selfIntro͕ॳظԽ͞ΕΔ // ໊લ͸γϩίϚͰ͢ cat.name = "ΫϩίϚ" print(cat.selfIntro) // ΫϩίϚ͸൓ө͞Εͳ͍ʂ // ໊લ͸γϩίϚͰ͢ ॳΊͯࢀরͨ͠ ඞཁʹͳͬͨ ࣌ʹॳظԽ͞ΕΔʂ
7. TXJGUʹ͸ओʹ
   छྨͷ࢖͍ํ͕͋Δ 
   MB[Z
   QSPQFSUZ
   
   MB[Z
   DPMMFDUJPO
8. MB[Z
   QSPQFSUZ
9. MB[Z
   QSPQFSUZ ɾMB[Zम০ࢠΛ͚ͭΔ͜ͱͰએݴͰ͖Δ
   ɾॳճΞΫηε࣌ʹ஋͕ॳظԽ͞ΕΔ
   ɾMB[Zम০ࢠ͸WBSʹ͔͚ͭ͠ΒΕͳ͍ class LazyCat { lazy var name = "γϩίϚ" }
10. ͳͥWBS͚ͩʁ ఆ਺ MFU ͸ΠϯελϯεͷॳظԽ׬ྃ࣌ʹ஋Λ อ͍࣋ͯ͠ͳ͚Ε͹ͳΒͳ͍ MB[ZΛ͚ͭΔͱॳظԽ࣌Ͱ͸ͳ͘ΞΫηε࣌ʹ ஋͕อ࣋͞ΕΔΑ͏ʹͳΔ
11. Կ͕خ͍͠ͷ͔ ɾॳظԽ࣌ʹ
    TFMG
    ͕࢖͑Δ
    ɾෆཁͳBMMPDBUJPO͕ൃੜ͠ͳ͍
12. class LazyCat { var name = "γϩίϚ" lazy var selfIntro: String = { return "໊લ͸\(self.name)Ͱ͢" }() var selfIntroduction: String = { return "໊લ͸\(self.name)Ͱ͢" }() // error: Use of unresolved identifier 'self' } DMPTVSF಺ͰΠϯελϯεม਺ʹΞΫηεͰ͖Δʂ ॳظԽ࣌ʹ
    TFMG
    ͕࢖͑Δ
13. class LazyCat { lazy var lazyName = name() var normalName = name() // Cannot use instance member 'name' within property initializer // property initializers run before 'self' is available func name() -> String { return "γϩίϚ" } } ΠϯελϯεϝιουͰॳظԽͰ͖Δ ॳظԽ࣌ʹ
    TFMG
    ͕࢖͑Δ
14. class LazyCat { lazy var ja = "ʹΌʙ" lazy var en = "mew" } let cat = LazyCat() // ͲͪΒ΋allocate͞Ε͍ͯͳ͍ print(cat.ja) // english͸allocate͞Εͳ͍ ඞཁͳ࣌ʹBMMPDBUJPO͕ൃੜ͢ΔͨΊ
    ϝϞϦΛઅ໿Ͱ͖Δ ෆཁͳBMMPDBUJPO͕ൃੜ͠ͳ͍
15. MB[Z
    DPMMFDUJPO
16. NBQ
    pMUFSͳͲ͕
    ஗ԆධՁ͞ΕΔDPMMFDUJPO
17. let array = Array(1...10) let lazyArray = array.lazy MB[ZͰऔಘͰ͖Δʂ
18. NBQ
    pMUFSͷධՁ
19. ௨ৗͷDPMMFDUJPOͷڍಈ let array = Array(1...10) let normalArray = array.map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 }
20. ௨ৗͷDPMMFDUJPOͷڍಈ let array = Array(1...10) let normalArray = array.map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 } 1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20
21. ௨ৗͷDPMMFDUJPOͷڍಈ let array = Array(1...10) let normalArray = array.map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 } print(normalArray.first) 1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 Optional(2)
22. ௨ৗͷDPMMFDUJPOͷڍಈ let array = Array(1...10) let normalArray = array.map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 } print(normalArray.first) 1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 Optional(2) <
    
    
    
    
    
    
    
    
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     NBQ
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    ^ pMUFS
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    ^ pSTU
23. ௨ৗͷDPMMFDUJPOͷڍಈ let array = Array(1...10) let normalArray = array.map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 } print(normalArray.first) 1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 Optional(2) <
    
    
    
    
    
    
    
    
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     NBQ
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    ^ pMUFS
    \
    
    
    
    ^ pSTU ແବ͕ଟ͍
24. MB[Z
    DPMMFDUJPOͷڍಈ let array = Array(1...10) let lazyArray = array.lazy .map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 }
25. MB[Z
    DPMMFDUJPOͷڍಈ let array = Array(1...10) let lazyArray = array.lazy .map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 } ϩά͕දࣔ͞Εͳ͍
26. MB[Z
    DPMMFDUJPOͷڍಈ let array = Array(1...10) let lazyArray = array.lazy .map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 } print(lazyArray.first) 1 2 Optional(2) pSTUʹΞΫηεͨ࣌͠ʢඞཁʹͳͬͨ࣌ʣʹ
    ඞཁͳ෼͚ͩNBQ
    pMUFS͕ධՁ͞ΕΔʂ
27. MB[Z
    DPMMFDUJPOͷڍಈ let array = Array(1...10) let lazyArray = array.lazy .map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 } print(lazyArray.first) 1 2 Optional(2) pSTUʹΞΫηεͨ࣌͠ʢඞཁʹͳͬͨ࣌ʣ
    ඞཁͳ෼͚ͩNBQ
    pMUFS͕ධՁ͞ΕΔʂ <
    
    
    
    
    
    
    
    
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    <>
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     NBQ
    \
    
    
    
    ^ pMUFS
    \
    
    
    
    ^ pSTU
28. MB[Z
    DPMMFDUJPOͷڍಈ let array = Array(1...10) let lazyArray = array.lazy .map { value -> Int in print(value) return value * 2 } .filter { value in print(value) return value < 10 } print(lazyArray.first) 1 2 Optional(2) pSTUʹΞΫηεͨ࣌͠ʢඞཁʹͳͬͨ࣌ʣ
    ඞཁͳ෼͚ͩNBQ
    pMUFS͕ධՁ͞ΕΔʂ <
    
    
    
    
    
    
    
    
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     NBQ
    \
    
    
    
    ^ pMUFS
    \
    
    
    
    ^ pSTU ແବ͕ͳ͍ʂ
29. ·ͱΊ TXJGUͷ஗ԆධՁ
    ɾMB[Z
    QSPQFSUZ
    ɾMB[Z
    DPMMFDUJPO
    MB[Z
    QSPQFSUZ
    ɾॳظԽ࣌ʹ
    TFMG
    Λ࢖͑Δ
    ɾϝϞϦΛઅ໿Ͱ͖Δ
    MB[Z
    DPMMFDUJPO
    ɾNBQ
    pMUFSར༻࣌ʹඞཁͳ෼͚ͩධՁ͞ΕΔ