Is it possible to extend DefaultValueAccessor?

var myobject = {};
_.extend(myobject, { 
  method: function() {
    return 'demo'
  } // ); <-- remove this
});

    import {Component,Renderer,ElementRef} from 'angular2/core';

    @Component({
      selector: 'child',
      template: '<div></div>',
    })
    export class ChildComponent {
      constructor(private _renderer: Renderer,
               private el: ElementRef) {
        (...)
      }
    }

var otherResolved = Injector.resolve([
  provide(DialogRef, { useValue: dialogRef})
  provide(Renderer, { useValue: this.renderer})
]);

import { 
  Input, forwardRef, Renderer2, 
  Injector, ElementRef, Directive
} from '@angular/core'

import { ControlValueAccessor, NG_VALUE_ACCESSOR, NgControl } from '@angular/forms';

export const PREV_VAL_VALUE_ACCESSOR: any = {
  provide: NG_VALUE_ACCESSOR,
  useExisting: forwardRef(() => PrevValDirective),
  multi: true
};

@Directive({
  selector: '[ngModel][prevVal]',
  host: {
    '(input)': 'handleInput($event.target.value)',
    '(blur)': 'onTouched()',
  },
  providers: [PREV_VAL_VALUE_ACCESSOR]
})
export class PrevValDirective implements ControlValueAccessor {
  @Input() prevVal: string;

  onChange = (_: any) => {};
  onTouched = () => {};

  constructor(
    private _renderer: Renderer2, 
    private _elementRef: ElementRef, 
    private _inj: Injector) {
  }

  writeValue(value: any): void {
    const normalizedValue = value == null ? '' : value;
    this._renderer.setProperty(this._elementRef.nativeElement, 'value', normalizedValue);
  }

  registerOnChange(fn: (_: any) => void): void {
    this.onChange = fn;
  }

  registerOnTouched(fn: () => void): void {
    this.onTouched = fn;
  }

  setDisabledState(isDisabled: boolean): void {
    this._renderer.setProperty(this._elementRef.nativeElement, 'disabled', isDisabled);
  }

  handleInput(value: any): void {
    if (value === this.prevVal) {
      let model = this._inj.get(NgControl);  // get NgModel
      model.control.setValue(model.value);   // set previous value
      return;
    }
    this.onChange(value);
  }
}

let model = this._inj.get(NgControl);

<input type="text" [(ngModel)]="val" prevVal="false">

<div [formGroup]="form">
    <jg-search formControlName="x" ngDefaultControl></jg-search>
                                   ^^^^^^^^^^^^^^^^
</div>

@Component({
  selector: 'jg-search',
  template: `
   <input [formControl]="ngControl.control">
  `
})
export class MyInput {
  constructor(public ngControl: NgControl) {}
}

import { ControlValueAccessor } from "@angular/forms";
// ...

export class MyClass implements ControlValueAccessor {

  // ...

  onChange = (_: any) => {};
  onTouched = () => {};

  // ...

  registerOnChange(fn: (_: any) => void): void { this.onChange = fn; }
  registerOnTouched(fn: () => void): void { this.onTouched = fn; }

  setDisabledState(isDisabled: boolean): void {
    this._renderer.setProperty(this._elementRef.nativeElement, 'disabled', isDisabled);
  }
}