angular - Extend a components change detection in Angular2 -

i have list object, this

class list {     private urls: string[] = [];      public getnames(): observable<string[]> {        // fetch `this.urls` , extract names     }      public addurl(url: string) {        this.urls.push(url);     }      public hash(): string {        // generate hash out of `this.urls`     } } 

it has urls, , can provide names found on these urls

now need component displays these names:

@component({     selector: 'lister',     template: '<p *ngfor="let name of names|async">{{ name }}</p>' }) class lister implements onchanges {       @input() list: list;       private names: observable<string[]>;       ngonchanges() {          this.names = this.list.getnames();      } } 

so far good, works if use this

 <lister [list]="somelist"></lister> 

but doesnt refresh when somelist.addurl(...) called, due fact not change anything.

a workaround introduce changes, this:

class lister implements onchanges {     // ...     @input() hash: string; } 

and use lister accordingly:

 <lister [list]="somelist" [hash]="somelist.hash()"></lister> 

but seem make unneccessary complex caller.

i'd rather somehome make lister "listen" it's lists changes.

is there way achieve this?

ok, clear case of rtfm: answer ngdocheck, called every time change detection run.