what is the relationship of NG_VALUE_ACCESSOR, ControlValueAccessor interface in angular?

what is the relationship of NG_VALUE_ACCESSOR, ControlValueAccessor interface in angular? Is if I have the following statement (provide:NG_VALUE_ACCESSOR)

@Component({
selector: 'rm-header',
templateUrl: './record-manager.component.html',
styleUrls: ['./record-manager.component.scss'],
providers: [{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => RecordManagerComponent),
multi: true
}]
})


then I already implement ControlValueAccessor, no need to explicitly writes

export class ComponentA implements ControlValueAccessor


?

but then I still need to implement: writeValue(), registerOnChange(), registerOnTouched(), and setDisabledState() defined in ControlValueAccessor interface?

Continue reading...