Road to RuboCop 1.0

Road to RuboCop 1.0 ,PJDIJ*50&4. *OD 3VCZ,BJHJ5BLFPVU Ride on RuboCop
1.0 for safe static analysis

!LPJD w 3VCP$PQDPSFUFBN w 044QSPHSBNNFS w 5FDITQFBLFS w %JTUJOHVJTIFE&OHJOFFSBU &4.
*OD

&4. *OD

Support OSS community

#VOEMFS 1SZ 34QFD 3VCP$PQ CZFCVH 3VCZ,BJHJ %3&$0.CPPUI

3VCP$PQDPSFEFWFMPQFST +0900 UTC+0200 +0300 +0800 -0400 .PSFUIBODPOUSJCVUPSTJOZFBST

3VCP$PQDPSFEFWFMPQFST +0900 UTC+0200 +0300 +0800 -0400 "VUIPS .PSFUIBODPOUSJCVUPSTJOZFBST

3VCP$PQDPSFEFWFMPQFST +0900 UTC+0200 +0300 +0800 -0400 .F .PSFUIBODPOUSJCVUPSTJOZFBST

3VCP$PQ"SDIJUFDUVSF

$VTUPNDPQT 3VOUJNFFOHJOFBOE DPSFDPQT /PEFQBUUFSOBOE OPEFFYUFOTJPOT 3VCZ"45QBSTFS 3VCP$PQ"SDIJUFDUVSF 1BSTFSHFN 3VCP$PQ"45
3VCP$PQDPSF 3VCP$PQ 34QFD 3VCP$PQ 1FSGPSNBODF 3VCP$PQ 3BJMT

$VTUPNDPQT 3VOUJNFFOHJOFBOE DPSFDPQT /PEFQBUUFSOBOE OPEFFYUFOTJPOT 3VCZ"45QBSTFS $VTUPN$PQT 1BSTFSHFN 3VCP$PQ"45 3VCP$PQDPSF
3VCP$PQ 34QFD 3VCP$PQ 1FSGPSNBODF 3VCP$PQ 3BJMT

$PQTHFNJpFE CZ3VCP$PQ)2

3VCP$PQDPSF 1BTU"SDIJUFDUVSF 1BSTFSHFN 3VCP$PQ 34QFD

(FNJpFEDPQT

SVCPDPQIRSVCPDPQ &YUSBDU1FSGPSNBODF$PQTJOUPBTFQBSBUFHFN

3VCP$PQDPSF 'JSTUFYUSBDUFEHFN 1BSTFSHFN 3VCP$PQ 34QFD 3VCP$PQ 1FSGPSNBODF &YUSBDUFE

+VBOJUP'BUBTGBTUSVCZSFQP

SBJMTSBJMT

#FODINBSLJQT require 'benchmark/ips' SLUG = 'writing-fast-ruby' def slow SLUG.gsub('-', '
') end def fast SLUG.tr('-', ' ') end Benchmark.ips do |x| x.report('String#gsub') { slow } x.report('String#tr') { fast } x.compare! end % ruby -v gsub-vs-tr.rb ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-darwin17] Warming up -------------------------------------- String#gsub 59.463k i/100ms String#tr 296.069k i/100ms Calculating ------------------------------------- String#gsub 598.537k (± 1.8%) i/s - 3.033M in 5.068466s String#tr 2.955M (± 0.9%) i/s - 14.803M in 5.009464s Comparison: String#tr: 2955357.8 i/s String#gsub: 598537.4 i/s - 4.94x (± 0.00) slower

w 3VCP$PQDPSFGPDVTPOQMBUGPSN JOEFQFOEFOU3VCZQFSGPSNBODF w 1FSGPSNBODFDPQGPDVTPO.3*`T QFSGPSNBODF w 5IFpSTUFYUSBDUFEHFN 3VCP$PQ (FNJGZOPUFT

w'JSTU `cp`DPNNBOEUPDPQZ GSPNUIFQFSGPSNBODFDPQ pMFTUPUIFOFXSFQPTJUPSZ w*UTFBTZ CVUJUSFNPWFTGit IJTUPSZ )PXXPVMEZPVHFNJGZ

w.BJOUBJOFSTXBOUUPUSBDF UIFSFBTPOGPSDIBOHFT GSPNUIFDIBOHFIJTUPSZ w*XPVMEMJLFUPLFFQ DPOUSJCVUPSOBNF (JUIJTUPSZJTNBUUFS

w*BTLFE!BNBUTVEB IPX,BNJOBSJEJWJEFE SFOEFSJOHFOHJOFT )PXXBTUIFSFQPTJUPSZLFQUIJTUPSZ

l *VTFEHJUDIFSSZQJDL XIFO*HBNJpFE,BNJOBSJ⚡ !BNBUTVEB

MPDBM SFNPUF(JU)VC 3VCP$PQ1FSGPSNBODF 1VMMOFXSFQP 3VCP$PQ1FSGPSNBODF 3VCP$PQ$PSF #BTFEPO 3VCP$PQ34QFD TUSVDUVSF %
git remote add upstream-performance \ <rubocop-performance URL> % git pull upstream-performance

MPDBM SFNPUF(JU)VC 3VCP$PQ1FSGPSNBODF 'FUDIPSJHJOBMSFQP 3VCP$PQ1FSGPSNBODF 3VCP$PQ$PSF % git remote add
upstream-core \ <rubocop URL> % git fetch upstream-core

MPDBM SFNPUF(JU)VC 3FQFBUDIFSSZQJDLT 3VCP$PQ1FSGPSNBODF .BOZNBOZ HJUDIFSSZQJDL 3VCP$PQ1FSGPSNBODF 3VCP$PQ$PSF % git
cherry-pick 7cbfa5a <hash of core> % git cherry-pick 7cbfa5a % git cherry-pick ...

MPDBM # DONE! % git push origin master SFNPUF(JU)VC 1VTIOFXSFQP
3VCP$PQ1FSGPSNBODF 3VCP$PQ$PSF 3VCP$PQ1FSGPSNBODF

wPWFSDIFSSZQJDLT )PXNBOZDIFSSZQJDLT % git log --oneline lib/rubocop/cop/performance \ spec/rubocop/cop/performance |
wc -l 225 % git log --oneline lib/rubocop/cop/rails \ spec/rubocop/cop/rails | wc -l 315 *NOPUTVSFJUJTUIFCFTUPQUJPO

SVCPDPQIRSVCPDPQ &YUSBDU3BJMT$PQTJOBTFQBSBUF

3VCP$PQDPSF 4FDPOEFYUSBDUFEHFN 1BSTFSHFN 3VCP$PQ 34QFD 3VCP$PQ 1FSGPSNBODF 3VCP$PQ 3BJMT &YUSBDUFE

w 3VCP$PQDPSFXJMMOPUTVQQPSU GSBNFXPSLTQFDJpDDPQT w 3VCP$PQ3BJMTOPXEFQFOETPO3BDL HFN w 5IFTFDPOEFYUSBDUFEHFN 3VCP$PQ
w 5IF3VCP$PQ3BJMTWFSTJPOJT (FNJGZOPUFT

lSVCPDPQSBJMTz FYJTUFEUP HFNJGZ SVCPDPQZNMJO SBJMTSBJMTSFQP /BNFTQBDFQSPCMFN 3VCP$PQ3BJMTW

w3VCP$PQ3BJMTWNJHSBUFE UPSVCPDPQSBJMT@DPOpHHFN w3VCP$PQ3BJMTWFYUSBDUFE 3BJMTDPQTGSPN3VCP$PQ DPSF 3VCP$PQ3BJMTWBOEW

w3VCP$PQ3BJMTXJMMESPQ 3BJMTTVQQPSU w3VCP$PQ3BJMTXJMMOPU BDDFQUDPQTGPSPMEFS3BJMT 3VCP$PQ3BJMTQMBOOFEDIBOHFT

3VCP$PQDPSF $VTUPN$PQT 1BSTFSHFN 3VCP$PQ 34QFD 3VCP$PQ 1FSGPSNBODF $VTUPN$PQ

w(FOFSBUFTEJSFDUPSZ TUSVDUVSFGPSZPVSHFN w$POUBJOTNPOLFZQBUDI DPEF #BELOPXIPX SVCPDPQFYUFOTJPOHFOFSBUPS

.POLFZQBUDIPO 3VCP$PQDPSF

w:PVDBODSFBUFBOFXSEQBSUZ 3VCP$PQHFNUPTVQQPSUMJCSBSZ TQFDJpD ZPVSQSPKFDU SFRVJSFNFOUT FUD w:PVDBOIBOEMFEPNBJO LOPXMFEHF 8IFOEPZPVDSFBUFBSEQBSUZHFN

SVCPDPQIRSVCPDPQSBJMT "EEOFXA3BJMT/FX(MPCBM.PEFMADPQ

1SPQPTBMTGPS &OGPSDF3BJMT&OHJOF

3VCP$PQ3BJMTUBSHFUTl3BJMTXBZz

IUUQTqFYQPSUFOHJOFFSJOHJTPMBUJOHSBJMTFOHJOFTXJUISVCPDPQGFBCB

3VCP$PQ"1*W

SVCPDPQIRSVCPDPQ *NQSPWJOHBVUPDPSSFDUJPOT"1*

< Base FYUFOE"VUP$PSSFDUPS EPcDPSSFDUPSc

w0ME"1*TXJMMOPUCFSFNPWFE TPPO CVU`Cop::Base`JT TUSPOHMZSFDPNNFOEFEOPX w4FFl6QHSBEF/PUFTzGPS EFUBJMT &YUFOTJPO"1*DIBOHFEGPSW

$VTUPNDPQT 3VOUJNFFOHJOFBOE DPSFDPQT /PEFQBUUFSOBOE OPEFFYUFOTJPOT 3VCZ`T"45QBSTFS 3VCP$PQ"45 1BSTFSHFN 3VCP$PQ"45 3VCP$PQDPSF

SVCPDPQIRSVCPDPQ 6TJOHSVCPDPQBTU

3VCP$PQDPSF 1BTU"SDIJUFDUVSF W 1BSTFSHFN 3VCP$PQ 34QFD 3VCP$PQ 1FSGPSNBODF 3VCP$PQ 3BJMT

5IJSEFYUSBDUFEHFN 1BSTFSHFN 3VCP$PQ"45 3VCP$PQ 34QFD 3VCP$PQ 1FSGPSNBODF 3VCP$PQ 3BJMT 3VCP$PQDPSF
&YUSBDUFE

w*OUFOEFEOPUGPS3VCP$PQ VTFSTEJSFDUMZ w3FFL B$-*UPPMXBOUUPVTF OPEFQBUUFSOTJOEFQFOEFOUMZ GSPN3VCP$PQDPSF 3VCP$PQ"45

USPFTTOFSSFFL SVCPDPQ

3VCP$PQ"45/PEF1BUUFSO w &YUFOEFETZOUBYGPS FYQSFTTJOHOPEFT w 1BUUFSONBUDIJOHUP DBQUVSFNBUDIJOH WBMVFT w 0GUFOVTFEBTBO
BSHVNFOUPG def_node_matcher FUD IUUQTHJUIVCDPNSVCPDPQIRSVCPDPQBTUCMPCNBTUFSMJCSVCPDPQBTUOPEF@QBUUFSOSC

3VCP$PQ"45/PEF w *OIFSJUT1BSTFS BOEQSPWJEFT QSFEJDBUF NFUIPET w :PVDBOSFGFS 3VCP$PQ JNQMFNFOUBUJPOT
IUUQTHJUIVCDPNSVCPDPQIRSVCPDPQBTUCMPCNBTUFSMJCSVCPDPQBTUOPEFSC

3VCP$PQ"451SPDFTTFE4PVSDF require 'rubocop-ast' ast = RuboCop::AST::ProcessedSource.new( 'puts "hello"', 2.7 ).ast
#=>s(:send, nil, :puts, s(:str, "hello")) ast.class #=> RuboCop::AST::SendNode ast.send_type? #=> true ast.first_argument.basic_literal? #=> true

3VCP$PQ"455SBWFSTBM require 'rubocop-ast' include RuboCop::AST::Traversal # Event handler for `send`
node def on_send(node) 'hi' end walk(ast) #=> hi

w4VQQPSUTTUBUJDBOBMZTJTCZ QBSTJOH QBUUFSONBUDIJOH BOEFWFOUIBOEMJOH w3VCP$PQJTUIF3FGFSFODF *NQMFNFOUBUJPO 3VCP$PQ"45JTBIBSWFTUFEMJCSBSZ

$VTUPNDPQT 3VOUJNFFOHJOFBOE DPSFDPQT /PEFQBUUFSOBOE OPEFFYUFOTJPOT 3VCZ`T"45QBSTFS 1BSTFS 1BSTFSHFN 3VCP$PQ"45 3VCP$PQDPSF

$PEFPG6OEFSXPSME

6OEFSUIF3VCP$PQ 1BSTFSHFN XIJUFRVBSLQBSTFS 3VCP$PQ"45 3VCP$PQ DPSF 0QBM 3VCZ/FYU :FU"OPUIFS "OBMZ[FS
3BDD

w3VCZQBSTFSXSJUUFOJO3VCZ w4VQQPSUT.3* +3VCZ 5SVGqF3VCZ w#/'JTXSJUUFOCZ3BDD CBTFEPOQBSTFZPG3VCZ 8IBU`T1BSTFSHFN

w/FX3VCZTZOUBYJOUSPEVDFEJO 1BSTFSBTFYQFSJNFOUBM w3VCP$PQ"45FYUFOET1BSTFS`T OFX"1* w$PQTDBOIBOEMFOFXTZOUBYUSFF OPEFT /FX3VCZTZOUBYDBOCFVTFEJO3VCP$PQ

XIJUFRVBSLQBSTFS SVCZZ"MMPXUSBJMJOHDPNNBJOIBTIQBUUFSO

8BUDIQBSTFZ DEdTSDHJUIVCDPNSVCZSVCZ HJUMPHQQBSTFZ DPNNJUEBGEDFBEBCBBGCBDDF "VUIPS,B[VLJ5TVKJNPUPLB[VLJ!DBMMDDOFU %BUF4VO.BS "MMPXUSBJMJOHDPNNBJOIBTIQBUUFSO EJ⒎HJUBQBSTFZCQBSTFZ JOEFYDDGCG
BQBSTFZ CQBSTFZ !! !!Q@LXBSHTQ@LXBSH Q@LXSFTU \ OFX@IBTI@QBUUFSO@UBJM Q OFX@VOJRVF@LFZ@IBTI Q ! ! ^

IUUQTHJUIVCDPNSVCZSVCZDPNNJUEBG

3VCZSFQPUFTUDPEF Trailing comma

QBSTFZ :BDD key: value key: value,

1VMM3FRVFTU

1BSTFSHFNUFTUDPEF 3VCZDPEF Trailing comma

#/'PG1BSTFSHFN 6TJOH3BDD key: value key: value,

$PNQBSFUXPPVUQVUT SVCZQBSTFW SVCZQBSTFCBTFEPOQBSTFSWFSTJPO SVCZQBSTFFDBTFQBUUFSOJO\B ^UIFOUSVF FOE DBTFNBUDI TFOEOJMQBUUFSO
JOQBUUFSO IBTIQBUUFSO QBJS TZNB JOU OJM USVF OJM SVCZQBSTFW SVCZQBSTFCBTFEPOQBSTFSWFSTJPO SVCZQBSTFFDBTFQBUUFSOJO\B^UIFOUSVF FOE DBTFNBUDI TFOEOJMQBUUFSO JOQBUUFSO IBTIQBUUFSO QBJS TZNB JOU OJM USVF OJM 4BNF"45

$VTUPNDPQT 3VOUJNFFOHJOFBOE DPSFDPQT /PEFQBUUFSOBOE OPEFFYUFOTJPOT 3VCZ`T"45QBSTFS "SDIJUFDUVSFUPXBSET 1BSTFSHFN 3VCP$PQ"45 3VCP$PQDPSF

$VTUPNDPQT 3VOUJNFFOHJOFBOE DPSFDPQT /PEFQBUUFSOBOE OPEFFYUFOTJPOT 3VCZ`T"45QBSTFS 3VCP$PQ$PSF 1BSTFSHFN 3VCP$PQ"45 3VCP$PQDPSF

$VTUPNDPQT 3VOUJNFFOHJOFBOE DPSFDPQT /PEFQBUUFSOBOE OPEFFYUFOTJPOT 3VCZ`T"45QBSTFS 3VCP$PQDPSFVQEBUF 1BSTFSHFN 3VCP$PQ"45 3VCP$PQDPSF

4BGFBOE 4BGF"VUP$PSSFDU

SVCPDPQIRSVCPDPQ *NQMFNFOUPQUJPOTUPSVOPOMZTBGFDPQTBOE TBGFBVUPDPSSFDUT

w3VCP$PQJTBTUBUJDBOBMZTJTUPPM BOESVOUJNFJOGPJTOPUBWBJMBCMF w'BMTFQPTJUJWFEFUFDUJPONBZIBQQFO w*ODPNQBUJCMFBVUPDPSFSFDUJPONBZ IBQQFO 8IZVOTBGF

&YBNQMFEFGBVMUZNM Lint/RaiseException: VersionAdded: 0.56 + Safe: false Style/DoubleNegation: VersionAdded: '0.19'
VersionChanged: '0.84' + SafeAutoCorrect: false

w*OEJDBUFTXIFUIFSUIFDPQ DBOZJFMEGBMTFQPTJUJWFT CZEFTJHO PSOPU 4BGF

&YBNQMF7BSJBCMF DPOTUBOU UZQFT # Performance/AncestorsInclude # bad A.ancestors.include?(B) # good
A <= B

w'BMTFQPTJUJWFGPS /PLPHJSJ9.-/PEFBODFTUPST w'SFRVFOUGBMTFQPTJUJWFTEVFUP UIFEJGGFSFODFCFUXFFO "DUJWF3FDPSEBOE1030JO3BJMT 6OTBGFBCPVUSFDFJWFSUZQF

w*OEJDBUFTXIFUIFSUIFBVUPDPSSFDUB DPQEPFTJTTBGF FRVJWBMFOU CZ EFTJHO w*GSafe: falseJTTFU UIFOSafeAutoCorrect: falseJTBMTPTFU
4BGF"VUP$PSSFDU

&YBNQMFAOJMAWBSJBCMF # Performance/StartWith cop # bad str =~ /\Aab/ #
good str.start_with?('ab')

w&SSPSJGUIFWBSJBCMFJTOJM w*UDBOCFBWPJEFECZBEEJOHB TBGFOBWJHBUJPOPQFSBUPS CVUJUJTOPUBMXBZTSJHIU 6OTBGFBCPVUOJMWBSJBCMF

&YBNQMFFYUFSOBMSFTPVSDFT # Rails/UniqBeforePluck cop # bad Model.pluck(:id).uniq # good Model.distinct.pluck(:id)

w$PNQBUJCJMJUZJTOPUHVBSBOUFFE CFUXFFO3VCZTuniqNFUIPE BOE3%#.`TDISTINCT w'PSFYBNQMF UIFEFGBVMU.Z42- DPMMBUJPOJTDBTFJOTFOTJUJWF 6OTBGFBCPVUFYUFSOBMSFTPVSDFT

3VCZ,BJHJDBODFMMFE

3VCPDPQ5ZQFE

803,*/130(3&44

SVCPDPQIRSVCPDPQ $-*PQUJPOTDIBOHFBVUPDPSSFDUOPXTBGFCZEFGBVMU

wTBGF wB BVUPDPSSFDU w" BVUPDPSSFDUBMM ASVCPDPQAPQUJPOTGPSTBGFVOTBGF

w"QQMZPOMZTBGFBVUPDPSSFDUJPO wGTUSJOHMJUFSBMDPNNFOUJTOPU BVUPDPSSFDUFECZEFGBVMUBTJU XBTCFGPSF #3&",*/($)"/(&⚠ B BVUPDPSSFDU

w"QQMZTBGFBOEVOTBGFBVUP DPSSFDUJPO w5IJTPQUJPOJTUIFTBNFABA CFIBWJPSPG3VCP$PQBOEMPXFS w-JLFAHJUCSBODIEAWTA%A " BVUPDPSSFDUBMM

/FXDPQTUBUVT

SVCPDPQIRSVCPDPQ .BLFJUQPTTJCMFUPFOBCMFEJTBCMFQFOEJOHDPQT

w/FXDPQTUBUVTTUBSUTXJUIQFOEJOH PSEJTBCMFE w"MMQFOEJOHDPQTBSFFOBCMFEXIFO UIFNBKPSWFSTJPOCVNQT w1MFBTFHJWFGFFECBDLJGZPVIBWF JTTVFTBCPVUOFXDPQT /FXDPQTUBUVT

4VQQPSUQPMJDZ

SVCPDPQIRSVCPDPQ 6QEBUFPCTPMFUFSVCJFTBOEBEEBEPDGPSDPNQBUJCJMJUZ

w3VCP$PQXJMMQSPWJEFTVQQPSU &0-FE3VCZGPSBCPVUBZFBS w1MFBTFNJHSBUFUPOFX WFSTJPOPG3VCZ 4VQQPSUQPMJDZ

0OFNPSFUIJOH

$VTUPNDPQT 3VOUJNFFOHJOFBOE DPSFDPQT /PEFQBUUFSOBOE OPEFFYUFOTJPOT 3VCZ`T"45QBSTFS 1BSTFSHFN 3VCP$PQ"45 3VCP$PQDPSF 3VCP$PQ
34QFD 3VCP$PQ 1FSGPSNBODF $POpHVSBUJPO SVCPDPQZNM #VJMUJODPQT

EPDTSVCPDPQPSH

)BQQZTPDJBMDPEJOH +0900 UTC+0200 +0300 +0800 -0400 XJUINBOZDPOUSJCVUPSTBOEZPV

3VCZ,BJHJNFNPSJBM

Road to RuboCop 1.0

Road to RuboCop 1.0

More Decks by Koichi ITO

Other Decks in Programming

Featured

Transcript