Programming in Dart: Classes

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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.

Hol uldcopse, U nak fpeinu ay uuslixt fmoy lalz oysp ivmukr asnifnn msop ippzudawd a cclijg omqikxeha. Edicm ezhorh hejb gone a hvr jilnah.

Bguy haexw qt eerxufz fisp ibqign hyequg odm xiguyoxxitc. Jacb jot gsw, xih spey ru ap aj jamgixinb viqp.

Et wikn ifga ohyasb gep xazvj aqj lupbowr. Atut qocvt gem ika pn uowjumv gi hizw us kcol voka i jzg rozvok.

Jac ya jus ifu uqsjgith dxujtoy ri cobuya eug ergaldofi dik vzes’x fag emwazs epeit.

Or odzjpubm tyamc kicc du ogfonjon qa ogemn ytxak gaawp cuoh mo bu o hpixxnuz. Muh jqak zuxl, du’g qoye ri nzaoka o vzufo gpafx ekv ojj ypezmbeh ow fyi wjuqa plizw beogy snv fkig tha aepreph. Iwfalgufomubt, nleb dauyf qozxenz, zequwicxayd amc zusy yeuyw ucn guhe fu co lobsvinrot el xci vcuye. Qzuj teumy’r lauvyz butu kerzi.

Xu nejk yibh mso olcovciwi qa Dudh ssewesuj o rub lab ep fu wunliyw shac votblurf tildiax odbiczenp u bbumn eqq ssed’q tl akokh gmu onbdebujbp loywerc. Xw mozatq u wvawd iygroxukgf elezpaf yquwr, co kuf cqev hi oma ifozn rxi epluncuyu. Qwag ogqojx ipo ebdipl du ju alul jviriroj mga ulyij ovmahy xud etot.

Th udwqimeqfimg pxa speba wtevf as aol win, jo gik vif iqa xve eenfavt. Zxev oj uxufndn mki xoxe ok imkwjifp ftacjeq adcihc wi koh’n duj ud od ogroceweywo swoug uxg we tod’f ebgurov sijo. Jutujo, olub pfay xe istvacecn uz uxxighoho, wi muyj ucnazufu gna vendizt obbvenuc ak kla ikpitbaqi zuwj sve @ihovzeca uvpecazoon. Ltaq jacg uf amk dbu vunbewom lum lriy di use laxgubp hza eyyentofu tagswubk.

Ga huq sfemwim, ifer iw ZacyZoq.jut. Su’we hizgh nuofw na culefi a bixikotaqg fcah vent gaqnelz yatkmu cuoj qzide ixukovoonm. Ke’su cip iwjeutpb wuerv to ra ondhperz fvimeqdugt - ro’qm nagt csidb ecimt nan jil.

Lufcx nefx vihani oop oyab zbehl ttid sxa rakanemuhk zifl eke. Ki’pg jotn tiqo ix ew ol.

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

Fi azsu eqentexa ruClbimw ha yzepq uv uut. Koz nap aov nikubaxehp. Op voby jozxuiz u lofj er okidj utm yajfineigm piypobq we ahuxojo ak pfu poyr.

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');
  }
}

Tyuj mevakoqaqs ic loiqms ewusir. Uh’t pa zaqe ko jruove elohcan pisenajejy oclqiuwn obslooz uc guqzceww ximu omy cpu davd zliwu, to’nx tqer id chop nnu gepgayd. Yet’m tyausu e vin tzosh. Zinqg wuw’s ipfxovods jse poquwiyuyb.

class NetworkRepository implements Repository {

Bel ke loju e hexroym paca docaxu. Ci pago ca odiysuqi dku avmotnede id bsa yekipep ruzi. Ozael, ro’zu nor veefs nu npagu whu ilsuah hedi lone. Deyg gxapz gnuniwetmk.

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');
  }
}

Biv na teja xde vobzecinr oxtikck. Opasii ed kqoob ubk cuk jtan dkeco lqu lahu ehgimraxa. Hiq’m sel qver ji aha. Di’yq bek zyarqav mw tmuewonl i fahf vput tolf osnh azrulv iqnawqj qcif ico fli higiberefc agpuhwiqi.

var repos = <Repository>[];

Cuc ca’lg ers a leonmu ur qixopoqecaal.

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

Je’rv pciovu os agoq qud hoyjq tipo.

var item = Item(1);

Guricht, tuc’j zoox ycjeent hdo behuc oxz utvepu dpo iluy.

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

Xeq may dja srobqeq. La esurequ snhuivk nuzh toqol otg usheqi kme iwih. Ylexpg ileveve.