typescript - Angular 2 - How does the directive give data to the host? -

i have think should pretty problem solve in angular 2, can't find right syntax.

my goal directive following:

1. accepts arbitrary data value. e.g., [my-data]="[1,2,3,4,5]"
2. processes on change. e.g. onchange() { return this.data.length = 55; }.
3. sends data host, , binds host property.

i'm fine on 1), little lost on 2) , 3). far have like:

@directive({   selector: ['ap-data'],   host: {     '(change)': 'onchange()'   } }) export class datadirective {    @input('ap-data') data: any;    @hostbinding('attr.ap-data') dataset() {     return processdata(this.data);   }    ...  }  @component({   selector: 'mycomponent',   directive: [datadirective],   template: `    <div [ap-data]="[1,2,3,4,5]"></div>   ` }) export class mycomponent {    public data: any[];    public dataset: processeddatatype;    ...  } 

for directive host binding use eventemitter:

@output('ap-data-change') apdatachange: eventemitter = new eventemitter()   onchange() {   ...    this.apdatachange.next(somevalue); }   <div [ap-data]="[1,2,3,4,5]" (ap-data-change)=hostfield=event$></div>