What's Cooking In Ruby 2.7

Transcript

1. 8IBUT
   $PPLJOH
   *O
   3VCZ
    
   ෢ऀ
   থل
   !LOV
2. ࣗݾ঺հ w ෢ऀ
   থل
   
   "LJOPSJ
   .VTIB
   w 5XJUUFS
   IUUQTUXJUUFSDPNLOV
   w (JU)VC
   IUUQTHJUIVCDPNLOV
   w גࣜձࣾϚνϚν
   w 3VCZίϛολʔ
   w 'SFF#4%ίϛολʔ
   w 5FBN
   /PLPHJSJ
   w )VHJOOڞಉ։ൃऀ
3. ࣗݾ঺հ w ࢓ࣄʢൈਮʣ
   w γʔαʔϒϩά͓Αͼ0&.αʔϏε
   w ΠʔϓϥεެࣜΞϓϦͷόοΫΤϯυ
   w ૬੮԰ެࣜΞϓϦͷόοΫΤϯυ
   w ۙ͝ॴ4/4ϚνϚν
   
4. ϚνϚν w גࣜձࣾϚνϚν
   w ໨ࠇ۠ɺֶܳେֶӺ͔Βెา෼
   w ձࣾ঺հ
   IUUQCJUMZNBDIJNBDIJJOUSP
   w ʮͻΒ͔Εͨɺͭͳ͕Γͷ͋Δ஍ҬࣾձΛͭ͘Δʯ
   w ۙ͝ॴ4/4
   ˍ
   ஍Ҭ৘ใϝσΟΞ
   IUUQTNBDIJNBDIJDPN
   w ΤϯδχΞ࠾༻தʂ
   IUUQTXXXXBOUFEMZDPNDPNQBOJFTNBDIJNBDIJJODQSPKFDUT
   w ϚνϚνΛࢧ͑Δٕज़$
   IUUQTUDP0.FIZ-:&
   3BJMT
   3FBDU
   1PTUHSF42-
   ʜ
   w ٕज़ϒϩά
   IUUQTUFDINBDIJNBDIJDPN
5. 3VCZͰͷ։ൃ׆ಈ w ϨϙδτϦ؅ཧऀ
   w ։ൃΠϯϑϥ੔උ
   w ඪ४ϥΠϒϥϦͷॆ࣮
   w %JHFTUͷ֦ுɺϋογϡΞϧΰϦζϜ௥Ճ
   w 4FUͷ࣮૷
   w CJHEFDJNBM
   TZTMPH
   JQBEES
   [MJCͳͲͷΠϯϙʔτࢧԉ΍อक
   w 4IFMMXPSETʹ
   TIFMMFTDBQF
   TIFMMKPJOΛ࣮૷
   w 3VCZ
   ͷϦϦʔε
6. 3VCZͰͷ։ൃ׆ಈ w ૊ࠐΫϥεͷ֦ு
   w "SSBZTMJDF
   w &OVNFSBUPSͷಋೖ
   &OVNFSBCMFͷ֦ு
   w FBDI@DPOT
   FBDI@TMJDF
   w FBDI@XJUI@PCKFDU
7. 3VCZͰͷ։ൃ׆ಈ w ࠷ۙ͸ɺ݄࣍ͷ3VCZ։ൃऀձٞʹग़੮ͯ͠ɺओʹ3BJMT 8FC։ൃऀͷ؍఺͔ΒΠϯϓοτͨ͠Γɺࣗ෼͕୲౰͢ ΔϥΠϒϥϦΛ͍͡Δ׆ಈ͕ϝΠϯͰ͢ɻ
8. 3VCZ
   ʹ޲͚ͯ w ·͕ͩग़͔ͯΒϲ݄͔͠ܦ͍ͬͯ·ͤΜ͕ɺ΍ʹ޲͚ͨػೳ։ൃ΍ٞ ࿦͸͍Ζ͍Ζਐߦ͍ͯ͠·͢ɻͦͷҰ୺Ͱ΋ɺָ͘͠͝঺հͰ͖ͨΒͱࢥ͍·͢ɻ
   w ͜͜Ͱ͝঺հ͢Δͷ͸͋͘·ͰዞҙతʹબΜͩྫʹա͗ͣɺ໢ཏੑ͸͋Γ·ͤΜɻ
   w ڵຯͷ͋Δํ͸/&84ϑΝΠϧɺ3VCZ։ൃऀձٞͷٞࣄ࿥ɺ3FENJOFͰͷν έοτϕʔεͷٞ࿦Λ௥͍͔͚·͠ΐ͏ɻ
   w ։ൃऀಉ࢜ͷٞ࿦͸ඇৗʹଟ૬తͰߴจ຺Ͱ͕͢ɺʮ͍ΖΜͳ͜ͱ͕͋ΔΜͩͳ͋ʯ ఔ౓ͷड͚औΓͰߏ͍·ͤΜɻ
   w ։ൃਞ΁ͷϑΟʔυόοΫ͸ɺ͍ΖΜͳνϟϯωϧΛ௨ͯ͡ؾܰʹͲ͏ͧʂ5XJUUFS ͰͭͿ΍͚ͩ͘Ͱ΋໨ʹೖΔ͔΋
9. ͓͠ͳ͕͖ w ೖͬͨ΋ͷ
   w ৽จ๏
   obj.:meth w ແϒϩοΫQSPDͷஈ֊తഇࢭ
   w &OVNFSBCMFUBMMZ
   w ٫Լ͞Εͨ΋ͷ
   w ։ൃதɾݕ౼தͷػೳ
   w ࠓޙͷ3VCZͷ༧ఆ
10. obj.:meth w obj.method(:meth)
    ͷ୹ॖจ๏
    w ϝιουΦϒδΣΫτΛऔΓग़͢
    w ैདྷͷ0CKFDUNFUIPE͸ϝιουݺͼग़ͩͬͨ͠
    w ϝιουΛऔΔͨΊʹϝιουΛݺͿඞཁ͕͋Δʜ
 ͍͔ʹ΋3VCZΒ͍͚͠Ͳʜ
    w ΦʔόʔϥΠυ͞Ε͍ͯΔ͔΋͠Εͳ͍
 ʢྫ
    3FRVFTU
    ΦϒδΣΫτ
    
    )551ϝιουΛฦ͢ʣ
    w 0CKFDUͰͳ͘#BTJD0CKFDUΛܧঝͨ͠ΦϒδΣΫτʹ͸NFUIPEϝιο υ͕ͳ͍
11. obj.:meth w ೚ҙͷΦϒδΣΫτʹରͯ͠ϝιουΛऔΓग़͍ͨ͠ͱ͖͸ɺΫϥε ͔ΒϝιουΛऔΓग़ͯ͠CJOE
    
    DBMM͢Δͱ͍͏ᷖԕͳखஈΛऔΔ ඞཁ͕͋ͬͨ
    • Object.instance_method(:method)
 .bind(obj)
 .call • ΦϒδΣΫτͷૉੑΛ໰ΘͣɺϝιουΛऔΓग़͢୹͍ه๏͕΄͍͠
    • ͍͔ͭ͘Ҋ͕͕͋ͬͨɺطଘจ๏ͱͷিಥ͕ͳ͘ɺγϯϘϧه๏ ͔ΒϝιουΛ࿈૝͠΍͍͢ʮobj.:methʯʹܾఆ
12. obj.:meth w ͨͱ͑͹ɺ͜͏͍͏ίʔυ͕୹͘ॻ͚ΔΑ͏ʹ
    w lines.map { |line| JSON.parse(line) }
 ↓
 lines.map(&JSON.:parse) • ͨͩ͠ɺself͸লུͰ͖ͳ͍͜ͱͱͨ͠
    w lines.each { |line| puts line }
 ↓
 lines.each(&self.:puts)
    w obj.each(&.:meth)Λڐͯ͠͠·͏ͱɺobj.each(&:meth)ͱݟͨ໨͕ ӝೋͭͳͷʹશવҧ͏ҙຯʹͳΔͷͰ໨ʹ༏͘͠ͳ͍ɺͱ͍͏.BU[ͷࢦఠʹ ΑΔ
13. ແϒϩοΫQSPDͷஈ֊తഇࢭ w ϝιουఆٛதͰϒϩοΫͳ͠ͷQSPDʹΑͬͯϝιουʹ౉͖ͬͯͨϒϩοΫΛ औಘ͢Δ͜ͱ͕Ͱ͖Δ
    • def each_key
 keys.each(&proc)
 end • proc͸Proc.newͱॻ͍ͯ΋ಉ͡ɺଞʹlambda΋͋Δ
    • block_given?ͰϒϩοΫ͕౉͞Ε͔ͨͲ͏͔Λ൑ఆͰ͖ɺyieldͰݺͼग़ͤ Δͷͱ߹Θͤͯɺ໌ࣔతʹҾ਺Λॻ͔ͳͯ͘΋౉͞ΕͨϒϩοΫΛར༻Ͱ͖ͨ
    w ͜ͷػೳΛഇࢭ͠Α͏ͱ͍͏ํ޲ʹͳͬͨ
    w ແϒϩοΫprocͱProc.new͸͔ΒܯࠂɺແϒϩοΫlambda͸ഇࢭ
14. ແϒϩοΫQSPDͷஈ֊తഇࢭ w എܠͱͯ͠͸ɺ࠷దԽ΍ޡΓݕग़ͷͨΊɺ͋Δϝιου͕ ϒϩοΫΛऔΔͷ͔Ͳ͏͔Λ੩తʹ൑ఆ͍ͨ͠ɺཧ૝తʹ ͸Ҿ਺ϦετͰ໌͍ࣔͤͨ͞ɺͱ͍͏ಈػ͕͋Δ
    w ϒϩοΫΛऔΒͳ͍ϝιουʹϒϩοΫΛ౉ͯ͠΋ɺϝ ιουଆͰνΣοΫ͠ͳ͍ݶΓΤϥʔ΍ܯࠂʹ͸ͳΒ ͳ͍
    w ࢖ΘΕΔͱࢥͬͯϒϩοΫΛ౉͕࣮ͨ͠͸࢖ΘΕͣແ ҙຯͱ͍͏ޡΓʹؾ͚ͮͳ͍ɺͱ͍͏໰୊
15. ແϒϩοΫQSPDͷஈ֊తഇࢭ w ͨͩɺ$3VCZʹ͸௕͍ؒɺdef method(&block)ͱϒϩοΫΛҾ਺Ͱ ड͚औΔͷ͸஗͍ͱ͍͏໰୊͕͋Γɺख़࿅޻͸ॻ͍ͯ͘Εͳ͔ͬͨ
    w yield͸ɺ౉͞ΕͨϒϩοΫΛ௚઀ݺͿ໋ྩʹίϯύΠϧ͞ΕΔ
    w ҰํɺԾҾ਺Ϧετʹ&blockͱॻ͘ͱɺϒϩοΫ͔Β1SPDΦϒδΣΫ τΛੜ੒্ͨ͠ͰɺϩʔΧϧม਺ʹ୅ೖ͞ΕΔ
    w ͞Βʹblock.callͱ͢ΔͱϩʔΧϧม਺Λࢀর͠ɺ1SPDΦϒδΣΫ τʹରͯ͠ϝιου͕ݺͼग़͞ΕΔ
    w Կεςοϓ΋ଟ͍ʜ
16. ແϒϩοΫQSPDͷஈ֊తഇࢭ w 3VCZ
    ͰɺԾҾ਺Ϧετʹ&blockͱॻ͍ͯ΋ɺ࣮ࡍʹblockΛ࢖͏ ·Ͱ1SPDΦϒδΣΫτͷੜ੒Λ஗Ԇ͢ΔΑ͏ʹͳͬͨ
    w தͰblock_given?ͱyieldΛ࢖ͬͨ··ɺϒϩοΫΛऔΔ͜ͱΛԾ Ҿ਺ϦετͰදݱͯ͠΋ੑೳ্ͷϖφϧςΟ͕ͳ͘ͳͬͨ
    w 3VCZ
    Ͱɺblock.call͸yieldͱಉ౳ͷੑೳʹͳͬͨ
    w ͨͩɺcallͷΦʔόʔϥΠυ༗ແΛ֬ೝ͢ΔͳͲ໘౗ͳ࣮૷ͷࣀ෺
    w ͜ΕͰɺ໌ࣔతʹ&blockͱblock.callΛ࢖͏ελΠϧΛਪ঑Ͱ͖ΔΑ ͏ʹͳͬͨ
17. ແϒϩοΫQSPDͷஈ֊తഇࢭ w ٯʹɺʮϒϩοΫΛऔΒͳ͍͜ͱʯΛ໌ࣔͰ͖ΔΑ͏ʹ͢΂͖͔ɺͱ͍ ͏ٞ࿦΋ਐΜͰ͍Δ
    w ౰ॳ͸ɺdef foo(&nil)ͱॻ͘͜ͱʹ͢Ε͹͍͍ͷͰ͸ɺͱ·ͱ ·Γ͔͚ͨ
    w ͔͠͠ɺͦ͏͢ΔͱʮϒϩοΫΛऔΒͳ͍ϝιου͢΂ͯʹ&nilΛ ೖΕΑ͏ʯͱ͍͏େྔͷ13͕Ұؾʹԡ͠دͤΔةዧ͕͋ΔͷͰऔ Γ΍Ίʹ
    w ݱࡏ͸ɺίϯύΠϧ࣌ͷ੩తղੳͰͰ͖ͳ͍͔ɺͱ͍͏औΓ૊Έ͕ࢼ͞ Ε͍ͯΔ
18. ແϒϩοΫQSPDͷஈ֊తഇࢭ w ͨͩɺTVQFSͱ͍͏น͕ൃݟ͞ΕΔ
    w super͋Δ͍͸super()ͱॻ͘ͱɺԿ΋ࢦఆ͍ͯ͠ͳ͍͕ɺ ౉͖ͬͯͨϒϩοΫΛεʔύʔϝιουʹ౉͢Α͏ʹͳ͍ͬͯΔ
    w superͷํ͸෼͔Δ͕ɺsuper()ͷํ͸Ұମͳͥʜ
    w ͦͷͨΊɺεʔύʔϝιου΋ḷͬͯݟͳ͍ͱϒϩοΫҾ਺Λ࢖ͬ ͍ͯΔͷ͔͸Θ͔Βͳ͍
    w ݱࡏ΋طଘͷϢʔβίʔυΛؚΊௐࠪɾݚڀ͕ਐߦத$
19. &OVNFSBCMFUBMMZ w ཁૉΛ஋ผʹ਺͑Δϝιου
    • ["a", "b", "b", "c", "a", "a"].tally
 # => { "a" => 3, "b" => 2, "c" => 1 } • SQLͷGROUP BY+COUNT()ͷΑ͏ͳ΋ͷ • ࠓ·Ͱ͸group_byΛ࢖ͬͯ͜Μͳ෩ʹͤ͟ΔΛಘͳ͔ͬͨॲཧ
    • ["a", "b", "b", "c", "a", "a"]
 .group_by(&:itself)
 .transform_values(&:size)
20. &OVNFSBCMFUBMMZ w ౰ॳ͸count_byͱ͍͏໊લͰɺϒϩοΫΛऔΔܗͰఏҊ͞Ε͍ͯͨʢϒϩοΫΛద ༻ͨ͠஋Ͱूܭ͢Δʣ
    w ͔͠͠ɺ͍͔ͭ͘ͷ೉఺ͰࢍಉΛಘΒΕͣ
    w ໊લ͕͍·͍ͪ
    countͱͷରশੑ͕ͳ͍ʢsort_bysort
    max_bymaxͳ Ͳ͔Βͷྨਪ͕ޮ͔ͳ͍ʣ
    w ػೳ͕ଟ͍
    ϒϩοΫΛऔΔͷ͸ΦϓγϣφϧͰ͸ʁඞཁͳΒmap͔ͯ͠Β౉ ͤ͹͍͍
    w γϡϫϧπม׵͍ͨ͜͠ͱ΋͋Δ͔΋͠Εͳ͍͕ɺ୅ද஋ΛͲ͏͢Δ͔࢓ ༷ΛܾΊ೉͍
    w tallyͱ͍͏໊લΛಘͯɺϒϩοΫΛऔΒͳ͍γϯϓϧͳܗͰ࠾༻
21. &OVNFSBCMFUBMMZ w UBMMZͱ͸਺Λ਺͑ͯه࿥͢Δ͜ͱͰɺࢴ΍ࠇ൘ʹҰຊͣͭઢΛॻ ͖ͳ͕ΒΧ΢ϯτ͢ΔͨΊͷه߸ͷݺশͰ΋͋Δʢ೔ຊͰͷʮਖ਼ʯ ʹ͋ͨΔه߸ɺʮ㠟ʯͷΑ͏ͳܗʣ
    w ͪͳΈʹ6OJDPEF
    Ͱʮਖ਼ʯͱͱ΋ʹೖΓ·ͨ͠
 IUUQTUXJUUFSDPNLFO@MVOEFTUBUVT 
22. ٫Լ͞Εͨ΋ͷ w BVUPMPBEͷഇࢭ⚡
    w .BU[͸εϨουηʔϑςΟͷ؍఺͔Βຊ࣭తʹةͳ͍ͷͰͣͬͱফͨ͠ ͍೿
    w 3BJMT͕DPOTU@NJTTJOHͰͷࣗಈϩʔυػߏΛ΍ΊͯBVUPMPBEΛ࢖͏ ;FJUXFSLΛͰ࠾༻ɺͱ͍͏͜ͷλΠϛϯάͰ͸͠͝Λ֎͢ͷ͔⽐ͱ ࢲͷதͰ૽વ
    w ͔͠͠3BJMTΞϓϦͷ։ൃͰ͸FBHFSMPBEJOHͩͱϓϩηεىಈɾ࠶ىಈ ͕ॏ͗͢ΔͷͰ͜͏͍͏ػߏ͸ඞਢͱઆಘ☝
    w গͳ͘ͱ΋3VCZ
    Yͷؒ͸࢒͢ɺͱ͍͏.BU[ͷݴ࣭Λಘͨ
23. ٫Լ͞Εͨ΋ͷ w BVUPMPBEͷഇࢭ
    w ͦͷޙɺBVUPMPBEΛΑΓ҆શʹ͢ΔͨΊͷݚڀͱվम͕ਐΜͰ ͍Δ
    w IUUQXXXBLSPSHEIUNMB@@
    w IUUQXXXBLSPSHEIUNMB@@@
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
24. ٫Լ͞Εͨ΋ͷ w "SSBZ΍)BTI΋ɺ4USJOHͷΑ͏ʹσϑΥϧτͰϑϦʔζ͢ΔϞʔυ͕΄͠ ͍ɺ͋Δ͍͸୯߲
    
    ͰEVQGSFF[F͍ͨ͠
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w ʮͦΜͳʹ΄͍͠ʁʯ·ͩջٙత
    w Ͱ΋3VCPDPQར༻ऀ͔Β͢Δͱɺఆ਺഑ྻɾϋογϡʹ.freezeΛ෇ ͚ͯճΒΕΔܦݧ͸ۤʑ͍͠ʜ
    w ͍ͣΕ·ͨνϟϯε͋Δ͔΋
25. ։ൃதɾݕ౼தͷػೳ w #FHJOMFTT
    4UBSUMFTT
    3BOHFT
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w &OEMFTT
    3BOHFT
    @ary[1..] ͕ೖͬͨͷͰɺࠓ౓͸ࠨ୺ଆΛলུͨ͠΋ͷ΋ ೖΕ͍ͨ
    w "DUJWF3FDPSEͳͲͷ%4-Ͱศར
    Product.where(price: ..1000)
    w &OEMFTT
    3BOHFT΋ಋೖޙʹ͍͔ͭ͘໰୊͕ൃݟɾରॲ͞ΕͨͷͰɺͦΕΒͷ ख౰͕ͯऴΘͬͯམͪண͍͔ͯΒ
    w &OVNFSBUPS:JFMEFSUP@QSPD
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
26. ։ൃதɾݕ౼தͷػೳ w σϑΥϧτϒϩοΫҾ਺
    @1
    @2
    ʜ
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w ͣͬͱ๬·Ε͍ͯΔػೳ
    numbers.map { "%02x" % @1 }
    w طଘจ๏ͱিಥͷͳ͍ح੻ͷҊʢ@1
    @2,…ʣʹظ଴
    w ύλʔϯϚονػೳʢDBTFJOߏจʣ
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w ڧ͘଴ͪ๬·Ε͖ͯͨػೳ
    w εΫϦϓτݴޠͷதͰ͸ڧྗͰ3VCZͷڧΈͱݴΘΕ͖͕ͯͨɺؔ਺ܕݴޠ͕ϝδϟʔ ʹͳ͖ͬͯͨࠓͰ͸ͪΐͬͱݟྼΓ͢Δ
27. ։ൃதɾݕ౼தͷػೳ w &4ελΠϧͷϋογϡ؆ศه๏ʢpFME
    QVOOJOHʣ
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w {
 name: name,
 type: type,
 created_at: created_at
 }
 ↓
 { name, type, created_at }
 
 ͳͲͱॻ͖͍ͨͳɺͱ͍͏ྫͷ΍ͭ
    w .+*5ʹΑΔ͞ΒͳΔߴ଎Խ
28. ࠓޙͷ3VCZͷ༧ఆ w ೥݄
    w ೔ʹ։ൃऀձٞ
    IUUQTCVHTSVCZMBOHPSHJTTVFT
    w 6OJDPEF
    ͕ग़ͨΒɺ3VCZ
    YΛϦϦʔε
    w ೥݄
    w 3VCZ,BJHJ
    
    ձظલ೔ʹ։ൃऀձٞ
    w ৽ݩ߸͕ൃද͞ΕͨΒ6OJDPEF
    ͕ग़Δ
    w ͦΕΛ଴ͬͯ3VCZ
    ZΛϦϦʔε
    w ຖ݄։ൃऀձٞ
    w νϟϯε͸ຖ݄
    IUUQTCVHTSVCZMBOHPSHJTTVFT
    w ೥݄
    w ೔
    3VCZ
    ϦϦʔε