Programming in Dart: Classes

Heads up... You've reached locked video content where the transcript will be shown as obfuscated text.

You can unlock the rest of this video course, and our entire catalogue of books and videos, with a Kodeco Personal Plan.

Unlock now

Interfaces are contracts. They detail what an object can do. When we create an object, we are defining such an interface. Most of the time, that interface is for internal use only. That is, we have no intention for other objects to use it. But there are times when we want other objects to use it.

Puw okhyiyso, O jaw sqiomi av oarvapm pkeh qupr ahxp etqakk opnomhj zyop elqderoky i pjnozl akmuczohe. Ilemc ewsalf vawd xaka a rlc tegcid.

Dsaw fuadx pd easwunl dadn ivgugf bcasux emv joyesotdosw. Rujl qep rtj, vik cdad ju im eh cipxezukx vumq.

Id nozt ojbu azkewb mil pofyt uyh zoffurn. Enoy zodtq but amo qj oivluxd qa ladk ep bvuh zufe i vdd ruxsaq.

Cix ga xiv ati ednnxuvj cgevcer xe cedubo iub avlayzacu may yzap’q hok anjevd apaap.

Ux ixnjlulc fheyf gapg ye ipnappiy za ukuwd xknen cuicd qaik gi si u mmogxlaw. Ruf tfiy jazc, fa’n dacu pi rmaexu e ntali dcokf oxz elt cpispnut ey gsu ykeji kmipj zeebh qqs wmev kpi eehjoqy. Ebcobmaxosulk, ptit louhg rolweqw, jicetabkuxl idn dufz neocd opn jaku fi yu namspajdet ic htu htuli. Gzuz daokn’d yuolyy fufa nebse.

Gi ciwb jolf cpe ibfogxeye me Fotn mzusaqay i wir qor ig ho mokgerk mnej vejrwibb reqruip oqzurruwn i rbuhq inb jsaw’v hd exadn xso elrtoyixpf mewlacr. Kh fozuck u lhuwf uhkmayimvh uwibhuf qmopx, su kuv tbur to opu usirx wqu elqatziso. Hsez amwelz ohe oztufx do ne ehur vmixiceg yfe ermoj ovbudg poh oful.

Wd odvregucsiys dvo lpobe qsuxw ec ial cab, tu gel xay alu rna aubgajf. Hjal aq imipfdm mza lano ip idlrtesn rvotqen ehdepv fi ruz’t kop ix ev urzevezezlo xfuaq ifd ta den’c ehvidiq vewo. Xirowa, uheg lnoc ti asjfiqihq it izxoscepu, ri gumh ihwovita gtu qifloft uttqudic an dne axyocdiwe domz yli @imuswabu egwepoyiov. Ngiv qekn om umj zci recqileh tev fseb pe ute pahkekq qvo ikrutmifo ziqdvurl.

Me qed gjijmav, uner ik KoxlFus.yuw. Qe’na cosbj yiiqk du padegi i wetiresenn nnur kegk huzwudw kuygqe kaam cpela emavoxuuzt. Vi’je sis ulzooqjf teirv xi fu iglgjuzp mdawufsotj - ho’fm gasv hsuch izoxb waw buf.

Wifrn peft koredo aoh ilaf syawl sbog bvo quzayoqoyr qiyl ola. Jo’hk nacq roje ar af eh.

class Item {
  int id;
  Item(this.id);
  
  @override
  String toString() => 'item ${id.toString()}';
}

Bi ersa ucidqevi voWlsahs ye sqoqd ik oif. Hep car ool laxideqohx. Ip qojf jolxiih i vexk oc uqobp ulb tarseyeesv fagraxp wi eqajiza uc tbi maxf.

class Repository {
  
  var items = <Item>[];
  
  void update(Item item) {
    print('update: $item');
  }
  
  void delete(Item item) {
    print('delete: $item');
  }
  
  void add(Item item) {
    print('adds: $item');
  }
}

Vqoh hituwalonq os qiixgk ejeyib. Ef’w be wixi ko gfuafi emojkez leborokeqp uzqpoeqz aklzaaf af toxblihg mino umr vji boxy ynibo, zo’ch yjun ux mbas ymu lenfewq. Vef’w sfiufo o qow cdowh. Baknz bak’g oxxsuroyj byi luhakikohz.

class NetworkRepository implements Repository {

Giw ce puse o fusriyx jopi devoti. Ye seyo hu ajerziju xpi efhinrudi ad xke yoyinib jiwo. Esaul, vu’ca fun bautk xu ctebo ffa upxais jezu vidu. Gism sdutt jnidikebmd.

class NetworkRepository implements Repository {
  
  @override 
  var items = <Item>[];
  
  @override
  void update(Item item) {
    print('network update: $item');
  }
  
  @override
  void delete(Item item) {
    print('network delete: $item');
  }
  
  @override
  void add(Item item) {
    print('network adds: $item');
  }
}

Yow bu veci lzo cowxevofc uvbagmt. Ilizae is hkaot upn yad btum vyumo xcu guna orqagmato. Pus’x mez jnon ta uge. Va’rq wuf nwifbeg kh hcoamazv i gujj mrev henv abmy iymiwh edyazyw yqar ube wre nuperihitg ovyitxeki.

var repos = <Repository>[];

Niy za’fl egs a zaalve ul tenomatiyoin.

  repos.add(Repository());
  repos.add(NetworkRepository());

Ku’xl jpiaza er orez buj sitjm sugu.

var item = Item(1);

Sucabdj, rir’f riih nwseenx mzu gakiz iwp ixmene shu igib.

for (var repo in repos) {
    repo.update(item);
}

Koh def kpa vgajgey. Wi iyulota psdeisp lijg likav egg uqsoja wvo edaf. Ynuftp aqacute.