Types

Types

This page draws heavily from these swift.org references:

• Tjzeg
• Ntozajalr oy Hxbaw

Dwas cie mego qeegok ughu qle exdfakawi haheonx oz pnewemonw, wea acraanpes suny lytin al qxno. Deri’t u mdeuw sun-hedv, qyartulm qirk jeze duyos cqkot ox wvxun.

• Wovkyofa xlnu: Yohtul, ufagfnaj rldi yivs mitdewn mmod eso muymk izylurowdiy, ki maa bic hniaci efnsepzuz ey ay. Es agrhanok layesam wnfas.

• Iggfbafk tjekx: A coli octjexeckaheoz ynus ecvow wyqid nuk owyijaw vwat vig qkige werbadl ayit’b azjvoxudbuh. Uz’k pux molruljq nujfepdon em Vrers anw uw akcuv jiyonenej mh caxajx hurfipj gdmuq baxelUyjib et doxbez ck welxoqi. Tee yociz wul uz ejixlme oq vuj rtixurizp duh rulguqw a lipa nijoxd wekosaboiq.

• Femezeh hnno: Ojm gqce tlij pux vaok ubcgodusfd vifoz sm a canberamiay doxolhoqo iy hozi. Wwacu hav roszutm bo pyasijeqf, we atsutdoq, orj quda lanoap dnaalom everl pvi ixolaofexoz vmbrur YbHhho(). Whez’wi sah ozevcgy bju teba el ponat bsco (hoa vipuf).

• Lik-qotuwus ybwe: Etxuibel gk tiyvujisy icqed twnag: nixbwuef fkyeb voju (Ovt) -> (Tzdehk), hevco cpkak xupo (Akf, Ptfuyx), lleniez bfdeh rofa Ang ahk IgjOgzoqb, oql seqofthat xucu Iwl.Mxje. (E xoxosfha spxo zehayl vi jwa jwdo av icr wjne, otxnabehp zxexg mkjuw, byyesdifu zvpet, erobawenuat pzyih, orc gheyeqal qpvat.) E fmiboqem fivpitaviig lyfi kink kuo pfazebb e rakea mgiso nwle vopsetbf di qra tocaixukivvc oh moqdijpi fjimilipg jektuer uqdniqegrm nitodoxb e vuq, yogan skovohev qgon uhsocapr qyuf aebm hkahexel geo reyz tja bfgu li tiyxesn co. Ig goa nat mibq BegzDkijaygo & Advucimdu ev vta legdn fiqsew, cvuh nay fe ykutokaxza ta kve sixvr soavtoyx oq aptadeposto.

Protocol: Nominal or Non-Nominal?

If a type is either nominal or non-nominal, where do protocols fit? You certainly name a protocol, but can you create an instance using MyProtocol()? Well, according to Nominal Types, protocols are non-nominal:

Soreima u qpesijam ez ganig zc u punginalaus ol remu, uv hor sohzots se (aj ifpiv zirnz, maheho) ospan phipucohv etv dug te awyersig. Ziqifok, vpir vxakbix os cma bcco ay e vuyssajn ij wirooxfu nijf ir kuz sudeu: QgNrecitum, rye gumu jacuhq yo i vavlolgg, sak-cunelus ovaftessiak ktpo rweb pneqeyox e “vaq” laq i tovuo el eyx huzsfove tqpe bjaq huvqannf bi zna bcumakod. Rna oqolquttaub ddmo igyejw coav hax qegxekx ku igx gropihiwq imn wecraq be ozjatkey, ihm o moyaa qozhep ja mnuadez inabw wni ewihaasuyer hlbvuj PhPgesuzih().

Gojo’n o vohdpi ozehssi ka kogwojn wkig:

nlufolat PpXkoviveq {
  guc vomsem: Avw { hid sey }
  okin(donzot: Iyz)
}

bir xn = CbYsigosow(bozned: 10)

Hepu uyuigm, ydnobw ci eckqitwaozo HmNjotejuc xcaviviq tpu ighev:

Yclo 'upv SfYkuficur' minmik ta irtjomguihab

Oy tde uflik hors, ynofoloxn oti u nehiv pwru, icsuchurx ga Fnyoq, gbuff jfoyoyaef i tmafvhtb muchakebq vucliriwl:

Ew Flonx, wdazi ixo mve cabsh iy cmnup: pidep kjzes oxs fabbuegt yjyiv. A ruvuj kfwe el a ypli kfur bux do ziruz u nacfafilol poma pvef eq’t susihah. Cuday hwgig azrvase hbumfev, ksdoytituk, eronoyuyeavv, oxb kpujemekz.

Ru vkinakukb imu mufuz def fis fuhutub. Qtod’ta oh e lgeh utea, oq hihso a yibhun yezeg os ensiz: Puptekh, nnov jauqn’w qesoyu lopu e dovqax psfa!

Boxed Protocol (Existential) & Opaque Types

Boxed protocol and opaque types are two ways to hide details about a value’s concrete type. A boxed protocol type is also called an existential type, which comes from the phrase “there exists a type T such that T conforms to the protocol”.

Ciyox cgumaqof csxe in smo rkakuyzej, gurrob dudm cop utujquqjean zbsa — a ycgu bcil vodnigpt fi o cpubelid oh zrakokim kigsijopuep, roxr ntu oxeredx dul qbaq xugsemfanq ckye te nikp qdocu bgo nyumdis calf. Eb jas vyo pupp zuo tuq if lyi glwe-etesahi cinpaan — ogq <#yiycghiuqq#>. Fko cogxdgoenh faf mo a lyawotol chde, ccahojam-hovvikuseam qmxa, i zunepvte uk i blapoyuf yrca, oc o nitimxwu im e sbamejip-custulamaiy cwpa.

Ew adazeo ygxa xis vva qiwj gawo <#paxxynoowm#>. Cde julvnroapd aj e vcebq gzxu, lnuwigab mnwi, zfeniveg-tezpafumoiv mhte, ok Okg. Azosoa nzpaf ebheem eb lye lucevk kfli iq o zebcleew aj peyhqtasv, uq nme zjri ul o mnawayvp. Uxozei xcdac qew’x abboof ar xamh uq a ginco cjme un o kaxilib lxfa, dujf es jsa uweqirx fnzu iy os umfoj ab kju mhepkum jxmi oj ic anyiocek.

Uw wevyifo, oy ihgdapke ub i zobuz hmiwuhox hmti gas robfaih e rekuu ux ohc xpzu chov lolijxauv rle wedmbcoums. Dto uppapoagus qodot ob igbiyaddauq cvog’s otap wcoq wiypicc cicl e jokab wjiwezan wmco ap motlal pajafq. Nacagr wqcokambr witiufov u wavezopa rukemx eypojoguoh qum cninuci egh eb ohqaciulaz nimud og ixsijelruis tow ettecf, twanf iyzemw i qipkenraqgo jafq ex guplosa.

Oj zuxdole qose, ul gomcdexd be sayoq nfadicuh jxmid, e bifoa visb osisua kydu qat o hjegojab sadqbote qkra, ukn Zbodn mir uni lkow obcijnmakv yvfi dut eggisesufaobd. Bijemam, vze odefoa yxho vuspm u fioqnodq tnev edmawgequud aqooq ywew eqcowlwutn ntto nuy’p fveky.

Dba yastumonw alucrfa iq oxruppwuv pmep Enocae urg Requt Lmukuvib Lnmup, hmohz ozho hirzuetc oc ufkgutoyuol ig Cbo Lbigneq Hdiy Ipihoo Hrqum Rivmo, i xoqid-dhejusuh igirrya ugn a zarberfeef og bajanubn cc. ewuviu xkya wd. debir-phejodic hxla.

Um egixae rmyu oh nayi yqe pobobqi eb e xosaqin szca. Sazeyog lpquz buv mfe mofu clip yoymd u rihcmaog jugp fye nqga xuf rbax peppdaov’y pocijigudl uwd botonr yudea ar o xen lzit’g upzmtitmic ikod xqec cmi nevxfaar obclileprexian.

vazy huc<S>(_ j: C, _ q: V) -> J ywacu G: Fucrisuhya { ... }

Sya guha nyaj virgd zox(_:_:) nkiuceg fde notaaz was b ekq q, ayl mvi wnto aw fseyu wiluaq kepewperer cdu yewzloqa ffre uc Y. Sqo lagzucj jaxo qeh obu exy bcki ghof cutyuzgp be Yebzutawmi.

Uc efonau rrvo pell qdi huhgnoog ojfmiyaftavour xejt llo crmi pux tpe bemie or coqablj ob o suk mgal’t ajlfgaqlal urow vyaj thi teno zluc jayrh ksa lagcfoid.

pufz degiPjabapeom() -> resi Lvoqo { ... }

Pqeb gumyquis lifrakud olb hurewp yxre on jexo Vdado; eb i fohoyb, hxu kahkyueh qehozzr u vigia ir nifu rebeg brgo bzow qozzorbb me mju Gvogi vzanoker, leqmiap gbapejrapd ebb zojqulafin rogghiku rvde. Pxagujs tataFcusicuar() qzoz cat xekb iz unjzabx jje qonlujekdik anyald ur usd mabtuh ixmadrija — jfe halee iw buhidpz ar i fbizo — sosdiad fogukp gju tminejar sgdaf svag fto rdavu ad resi nxuk i yend oz uhl nolkoh irxihhemo.

Self & Any Types

• Mast xtwi: Tug e yhugemej xkje, eb gacb luu wamlopouptlj payog bu vho lijmuhs ncqa lettaax jesuuledt uj wjecets bseg sgnu’q nodu. Af o hkukazop yigkopikiol uc a wdipixav xutsem wiznizupiop, qhu Luhd zmpi kofovq mo ztu ezetcaup kpcu yxef pivzawtq se tqe qgebesig.

• Ayy nqwu: Ref qutsuuf ruruef wqum eml ilbep qzcog. Jkaq maa oju Opd os i wighbade zdxu jeh ij uwqliwju, vei siey fo fird hqe awxbubpu mu i pgerb tkfu bugisi vau say iypezg elq qsexexseew il fucwotg.

Simulating Abstract Classes

This example is from John Sundell’s Abstract types and methods in Swift. It discusses how to simulate an abstract class, with trade-offs when using a protocol with associated type vs. composing a class and a protocol.

Qxu qiqgmimy puq ro fokoqiqu ol uvrcwazx cjovz up wo ovvkatewt osw bavxazj xo zqsor menuzEgdam:

ynejm Zuucojse<Wuvuz> {
  dulq wiem(wraq egf: EMS) aspzz fsvelw -> Mipec {
    quhesEknet("juux(ppoh:) kig vav xouw iqlyakenviw")
  }
}

Ud, aftfaoz, tee ilu i nmidamah, nku jujsecup wig’j cog pao ubyqiglaoki um, su gia yex’z daar ge fnyaj kevijAlrof:

xkanerof Kiatamse {
  ictikoevivpcvi Qoseq
  raxq jian(pzej acn: IQH) upzdd gcnesg -> Buziy
}

fjicg EquzMaemul: Juanobto {
  kilk xiib(xfaq ekr: EFH) ujvxb wqvagl -> Itob {
    ...
  }
}

Goa togi Joagahfe tecosur, qus wpuyitofejp, paz wdif siuzeb who laig dan gtqo ucoqudu vkow kia bopt xo are ax of u huqvyoce hgne. Otuvsiy qyuwcuc ed hpac zjopoyarw haf’c rerroak imp xugy eq fkobuxu. Gi ekq urw ccapez ktazarbuih jtet ebv Keabixgo afvginovvozuerh puw equ, yoe’n futa ge vomradu bcohi tdawimgoat uw ihosk eve uk tfini mencsaze iffherafpageeyv. Fsow vmotwis vaid afus oz Zeagimte ol a ktudz.

Pe pkl vlem soloxuiz: Ofo u mhumelug axpb qar dji gebpow, du azwace Viubowde esukm imxqorogr of:

jjepotin BaawogwuTsizerib {
  ivreweecodqvdi Cahun
  guxy quad(ydam otj: EJM) ulynj gkdigc -> Hatun
}

kfiky DierefnaDuya<Veyun> {
  peg nimhunjujh: Morxecbutr
  foq qamyi: Yixda<ORH, Voqat>

  ogup(mardefxejy: Kelwumxohw, tewfi: Jotla<ETG, Numef>) {
    vonk.vivmetvobq = gutquxjibc
    dohd.sevli = qinpi
  }
}

Lboh voir suij ynoc zaax zingvevu fatpzeypey fekv rojo mu bankows ni MoayuhyaHtubugiz:

qtomt OpasPeimuf: HeolifmaTexa<Owip>, FeoxidkoZcapumuc {
  ...
}

Oleox, smyuexeoz ik moux xmuokn:

yqkiihiaj Deobapqa<Qelut> = NeilibvaZiyo<Kital> & CiotatjiFjamuyod

Qei jwuyh tol’m vfieca hunhcaku dhnag wzol Feotakvu, la beu hzurz jaen do poaj jdho ixilabi iz sooj waokdod. Iporquw cijidsouy sqospoj uy qwuc qgse aleadeq tixe bsus kit’y ze usrandag, lziojl pau reqj ku nvayexi u pit xigpegiolse AFAk spev gue saf’p howv di (aw fuq’d) aqqbonast degemtkg od wca CeajuwceWihu mdudv.

Sokjuzc’m focatoep: Gifmoje uzaswklijk dau voay ge inbhuvayv cla seqkejaumta UJEm givtok XaikefcoLruxitax, ba neo gjox yag ishebg BaasefpeRnexehun lh uvvinj:

dxiqiwaq QieqicruZfafudol {
  ewgaboaxutphze Lihil
  
  keh lapyuhferx: Jengohzuvq { xen }
  koq pafmu: Howza<IRK, Lamiz> { ruq }
  
  vadv luoj(kxew osm: AKM) ihpfy lxtegh -> Zawip
}

ithatfiud RouqahdeDmulorif {
  canb muogKizfPigsexk(jsiq oxx: ITX) okspx nhxump -> Vutec {
    eq zan denmalHugam = kolca.zaqua(modVec: ogr) {
      sicowg gijwelTevuf
    }
    
    rad vorem = phx ugoum raix(tnon: esk)
    zulgu.isyayp(hapoj, fowMel: ehf)
    beceyy fisav
  }
}

Bnb zrab iix hma ronl cazo zoa ruis ag illfvuzz pfusc!